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Sample records for incipient melting point

  1. Study of formation mechanism of incipient melting in thixo-cast Al–Si–Cu–Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Du, Kang, E-mail: du126kang@126.com; Zhu, Qiang, E-mail: zhu.qiang@grinm.com; Li, Daquan, E-mail: lidaquan@grinm.com; Zhang, Fan, E-mail: sk_zf@163.com

    2015-08-15

    Mechanical properties of thixo-cast Al–Si–Cu–Mg alloys can be enhanced by T61 heat treatment. Copper and magnesium atoms in aluminum matrix can form homogeneously distributed precipitations after solution and aging treatment which harden the alloys. However, microsegregation of these alloying elements could form numerous tiny multi-compound phases during solidification. These phases could cause incipient melting defects in subsequent heat treatment process and degrade the macro-mechanical properties of productions. This study is to present heterogeneous distribution of Cu, Si, and Mg elements and formation of incipient melting defects (pores). In this study, incipient melting pores that occurred during solution treatment at various temperatures, even lower than common melting points of various intermetallic phases, were identified, in terms of a method of investigating the same surface area in the samples before and after solution treatment in a vacuum environment. The results also show that the incipient melting mostly originates at the clusters with fine intermetallic particles while also some at the edge of block-like Al{sub 2}Cu. The fine particles were determined being Al{sub 2}Cu, Al{sub 5}Cu{sub 2}Mg{sub 8}Si{sub 6} and Al{sub 8}Mg{sub 3}FeSi{sub 2}. Tendency of the incipient melting decreases with decreases of the width of the clusters. The formation mechanism of incipient melting pores in solution treatment process was discussed using both the Fick law and the LSW theory. Finally, a criterion of solution treatment to avoid incipient melting pores for the thixo-cast alloys is proposed. - Highlights: • In-situ comparison technique was used to analysis the change of eutectic phases. • The ralationship between eutectic phase size and incipient melting was studied. • Teat treatment criterion for higher incipient melting resistance was proposed.

  2. Geochemical Consequence of Extraction of Incipient CO2-rich melts from Earth's Deep Upper Mantle

    Science.gov (United States)

    Dasgupta, R.; Withers, A. C.; McDonough, W. F.; Hirschmann, M. M.

    2007-12-01

    The initiation of partial melting beneath mid-oceanic ridges and ocean islands likely produces incipient carbonatitic melts. These highly mobile melts generated at great depth may not only affect geophysical properties of deep upper mantle but can also influence Earth's geochemical evolution by releasing incompatible parent and/or daughter elements, heat producing elements, and volatiles. But constraints on the fractionation of the key trace elements between the peridotitic residue and carbonatitic melts are lacking at conditions of initiation of partial melting beneath ridges.Experiments at 6.6-8.6 GPa and 1265-1470 °C on carbonated peridotite doped with a blend of trace elements produced cpx + garnet + magnesite ± opx ± olivine + carbonatitic melt (cbL) similar in composition to that expected at the solidus of carbonated peridotite (Ca# = 0.52 at 6.6 GPa and 0.45 at 8.6 GPa; Na2O = ~4 wt.% at 6.6 GPa and ~2.5 wt.% at 8.6 GPa). Compared to previous studies at lower pressures (2.0-4.6 GPa), Dcpx/cbL from the present study are smaller for elements substituting into the cpx M2 site, especially trivalent cations ( DLu = 0.17, DLa = 0.006). Dcpx/cbL for U (0.001) and Th (0.002) are also noticeably lower than the previous estimates. In contrast, Dgarnet/cbL values are higher for REEs ( DLu = 4.6, DLa = 0.039) and HFSEs, U (0.023) and Th (0.017).Our estimate of Dperidotite/cbL indicates that incipient carbonatite extraction from the deep upper mantle will produce a residue with a more depleted Rb/Sr, U/Pb, Th/U, and enriched Sm/Nd, which may evolve to produce the most common of the mantle end member components, PREMA. Metasomatic implantation of deep carbonatitic melt into the lithosphere can generate a high-μ (238U/204Pb) signature, whereas mixing of carbonatite with elevated Th/U can contribute to the observed 230Th-excesses in MORBs. However, carbonatites derived by incipient melting of depleted (DMM) mantle have limited trace element enrichments, ~10-100

  3. Relationships between melting point and boiling point of organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yalkowsky, S.H.; Krzyzaniak, J.F.; Myrdal, P.B. (Univ. of Arizona, Tucson, AZ (United States). College of Pharmacy)

    1994-07-01

    Relationships between melting point and boiling point are shown to be dependent upon the molecular symmetry number and a modified count of the total number of atoms in the molecule. Using the above relationships, the boiling and melting points of nearly 1,000 non-hydrogen-bonding organic compounds have been correlated. The correlations for boiling point and melting point have root mean square errors of 28 and 36 C, respectively.

  4. Nanotexturing of surfaces to reduce melting point.

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Ernest J.; Zubia, David (University of Texas at El Paso El Paso, TX); Mireles, Jose (Universidad Aut%C3%94onoma de Ciudad Ju%C3%94arez Ciudad Ju%C3%94arez, Mexico); Marquez, Noel (University of Texas at El Paso El Paso, TX); Quinones, Stella (University of Texas at El Paso El Paso, TX)

    2011-11-01

    This investigation examined the use of nano-patterned structures on Silicon-on-Insulator (SOI) material to reduce the bulk material melting point (1414 C). It has been found that sharp-tipped and other similar structures have a propensity to move to the lower energy states of spherical structures and as a result exhibit lower melting points than the bulk material. Such a reduction of the melting point would offer a number of interesting opportunities for bonding in microsystems packaging applications. Nano patterning process capabilities were developed to create the required structures for the investigation. One of the technical challenges of the project was understanding and creating the specialized conditions required to observe the melting and reshaping phenomena. Through systematic experimentation and review of the literature these conditions were determined and used to conduct phase change experiments. Melting temperatures as low as 1030 C were observed.

  5. Making Sense of Boiling Points and Melting Points

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 6. Making Sense of Boiling Points and Melting Points. S Prahlada Rao Shravan Sunkada. General Article Volume 12 Issue 6 June 2007 pp 43-57. Fulltext. Click here to view fulltext PDF. Permanent link:

  6. Making Sense of Boiling Points and Melting Points

    Indian Academy of Sciences (India)

    The boiling and melting points of a pure substance are char- acteristic physical constants of that substance in its pure state. Although it is not possible to predict these physical constants for a given substance, it is, however, possible to rationalize these values on a relative basis for given substances, taking into account the ...

  7. Low-melting point heat transfer fluid

    Science.gov (United States)

    Cordaro, Joseph Gabriel; Bradshaw, Robert W.

    2010-11-09

    A low-melting point, heat transfer fluid made of a mixture of five inorganic salts including about 29.1-33.5 mol % LiNO.sub.3, 0-3.9 mol % NaNO.sub.3, 2.4-8.2 mol % KNO.sub.3, 18.6-19.9 mol % NaNO.sub.2, and 40-45.6 mol % KNO.sub.2. These compositions can have liquidus temperatures below 80.degree. C. for some compositions.

  8. Realization of Copper Melting Point for Thermocouple Calibrations

    Directory of Open Access Journals (Sweden)

    Y. A. ABDELAZIZ

    2011-08-01

    Full Text Available Although the temperature stability and uncertainty of the freezing plateau is better than that of the melting plateau in most of the thermometry fixed points, but realization of melting plateaus are easier than that of freezing plateaus for metal fixed points. It will be convenient if the melting points can be used instead of the freezing points in calibration of standard noble metal thermocouples because of easier realization and longer plateau duration of melting plateaus. In this work a comparison between the melting and freezing points of copper (Cu was carried out using standard noble metal thermocouples. Platinum - platinum 10 % rhodium (type S, platinum – 30 % rhodium / platinum 6 % rhodium (type B and platinum - palladium (Pt/Pd thermocouples are used in this study. Uncertainty budget analysis of the melting points and freezing points is presented. The experimental results show that it is possible to replace the freezing point with the melting point of copper cell in the calibration of standard noble metal thermocouples in secondary-level laboratories if the optimal methods of realization of melting points are used.

  9. On changes in melting points of some lanthanide complexes

    International Nuclear Information System (INIS)

    Meshkova, S.B.; Poluehktov, N.S.; Korovin, Yu.V.

    1983-01-01

    An expression for calculation of melting points of complexes of trivalent lanthanide ions with account for the number of f-electrons, S orbital quantum number of the ground state and the of spin-orbit interaction energy is given. Good agreement of calculated melting points with those determined experimentally supports the consistency of the suggested conrelation

  10. Estimating the melting point, entropy of fusion, and enthalpy of ...

    Science.gov (United States)

    The entropies of fusion, enthalies of fusion, and melting points of organic compounds can be estimated through three models developed using the SPARC (SPARC Performs Automated Reasoning in Chemistry) platform. The entropy of fusion is modeled through a combination of interaction terms and physical descriptors. The enthalpy of fusion is modeled as a function of the entropy of fusion, boiling point, and fexibility of the molecule. The melting point model is the enthlapy of fusion divided by the entropy of fusion. These models were developed in part to improve SPARC's vapor pressure and solubility models. These models have been tested on 904 unique compounds. The entropy model has a RMS of 12.5 J mol-1K-1. The enthalpy model has a RMS of 4.87 kJ mol-1. The melting point model has a RMS of 54.4°C. Published in the journal, SAR and QSAR in Environmental Research

  11. Thermal diffusivity of UO2 up to the melting point

    Science.gov (United States)

    Vlahovic, L.; Staicu, D.; Küst, A.; Konings, R. J. M.

    2018-02-01

    The thermal diffusivity of uranium dioxide was measured from 500 to 3060 K with two different set-ups, both based on the laser-flash technique. Above 1600 K the measurements were performed with an advanced laser-flash technique, which was slightly improved in comparison with a former work. In the temperature range 500-2000 K the thermal diffusivity is decreasing, then relatively constant up to 2700 K, and tends to increase by approaching the melting point. The measurements of the thermal diffusivity in the vicinity of the melting point are possible under certain conditions, and are discussed in this paper.

  12. Making Sense of Boiling Points and Melting Points

    Indian Academy of Sciences (India)

    to rationalize the trends in these physical constants based on non- covalent interactions and symmetry, .... the product of distance d between the two points and the magni- tude of charge e gives the magnitude of the ... Individual bond moments in a molecule add up in vector fashion to result in the net dipole moment for the ...

  13. Statistical distribution of thermal vacancies close to the melting point

    Energy Technology Data Exchange (ETDEWEB)

    José Pozo, María, E-mail: mariaj.pozom@gmail.com [Grupo de Nanomateriales, Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Davis, Sergio, E-mail: sdavis@gnm.cl [Grupo de Nanomateriales, Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Peralta, Joaquín, E-mail: joaquin.peralta@unab.cl [Departamento de Ciencias Físicas, Facultad de Ciencias Exactas, Universidad Andrés Bello, Santiago (Chile)

    2015-01-15

    A detailed description of the statistical distribution of thermal vacancies in an homogeneous crystal near its melting point is presented, using the embedded atom model for copper as an example. As the temperature increase, the average number of thermal vacancies generated by atoms migrating to neighboring sites increases according to Arrhenius’ law. We present for the first time a model for the statistical distribution of thermal vacancies, which according to our atomistic computer simulations follow a Gamma distribution. All the simulations are carried out by classical molecular dynamics and the recognition of vacancies is achieved via a recently developed algorithm. Our results could be useful in the further development of a theory explaining the mechanism of homogeneous melting, which seems to be mediated by the accumulation of thermal vacancies near the melting point.

  14. Low-melting point inorganic nitrate salt heat transfer fluid

    Science.gov (United States)

    Bradshaw, Robert W [Livermore, CA; Brosseau, Douglas A [Albuquerque, NM

    2009-09-15

    A low-melting point, heat transfer fluid made of a mixture of four inorganic nitrate salts: 9-18 wt % NaNO.sub.3, 40-52 wt % KNO.sub.3, 13-21 wt % LiNO.sub.3, and 20-27 wt % Ca(NO.sub.3).sub.2. These compositions can have liquidus temperatures less than 100 C; thermal stability limits greater than 500 C; and viscosity in the range of 5-6 cP at 300 C; and 2-3 cP at 400 C.

  15. Gibbs free energy, surface stress and melting point of nanoparticle

    International Nuclear Information System (INIS)

    Luo, Wenhua; Hu, Wangyu

    2013-01-01

    Two approaches to calculating Gibbs free energy of nanoparticle are compared. It is found that the contribution from the vibrational entropy of surface atoms of nanoparticle to its Gibbs free energy can be ignored, and Jiang et al.'s formula [J. Phys. Chem. B 105 (2001) 6275] [27] for calculating surface stress is only valid around room temperature. Furthermore, an approximate relationship between surface stress and surface free energy of nanoparticles is revealed. Finally, the reason why effect of size dependent surface energy on melting point of nanoparticle was neglected is clarified

  16. On the correlation between hydrogen bonding and melting points in the inositols

    Directory of Open Access Journals (Sweden)

    Sándor L. Bekö

    2014-01-01

    Full Text Available Inositol, 1,2,3,4,5,6-hexahydroxycyclohexane, exists in nine stereoisomers with different crystal structures and melting points. In a previous paper on the relationship between the melting points of the inositols and the hydrogen-bonding patterns in their crystal structures [Simperler et al. (2006. CrystEngComm 8, 589], it was noted that although all inositol crystal structures known at that time contained 12 hydrogen bonds per molecule, their melting points span a large range of about 170 °C. Our preliminary investigations suggested that the highest melting point must be corrected for the effect of molecular symmetry, and that the three lowest melting points may need to be revised. This prompted a full investigation, with additional experiments on six of the nine inositols. Thirteen new phases were discovered; for all of these their crystal structures were examined. The crystal structures of eight ordered phases could be determined, of which seven were obtained from laboratory X-ray powder diffraction data. Five additional phases turned out to be rotator phases and only their unit cells could be determined. Two previously unknown melting points were measured, as well as most enthalpies of melting. Several previously reported melting points were shown to be solid-to-solid phase transitions or decomposition points. Our experiments have revealed a complex picture of phases, rotator phases and phase transitions, in which a simple correlation between melting points and hydrogen-bonding patterns is not feasible.

  17. On the correlation between hydrogen bonding and melting points in the inositols

    DEFF Research Database (Denmark)

    Bekö, Sándor L; Alig, Edith; Schmidt, Martin U

    2014-01-01

    Inositol, 1,2,3,4,5,6-hexahydroxycyclohexane, exists in nine stereoisomers with different crystal structures and melting points. In a previous paper on the relationship between the melting points of the inositols and the hydrogen-bonding patterns in their crystal structures [Simperler et al. (2006...... ▶). CrystEngComm 8, 589], it was noted that although all inositol crystal structures known at that time contained 12 hydrogen bonds per molecule, their melting points span a large range of about 170 °C. Our preliminary investigations suggested that the highest melting point must be corrected for the effect...... ordered phases could be determined, of which seven were obtained from laboratory X-ray powder diffraction data. Five additional phases turned out to be rotator phases and only their unit cells could be determined. Two previously unknown melting points were measured, as well as most enthalpies of melting...

  18. 46 CFR 153.908 - Cargo viscosity and melting point information; measuring cargo temperature during discharge...

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Cargo viscosity and melting point information; measuring... Cargo viscosity and melting point information; measuring cargo temperature during discharge: Categories... lading, a written statement of the following: (1) For Category A or B NLS, the cargo's viscosity at 20 °C...

  19. Pre-transition phenomena in CdTe near the melting point

    Science.gov (United States)

    Shcherbak, L.

    1999-02-01

    The influence of slight (up to 2 mol%) CdTe doping by In or Ge on the post-melting effect in CdTe as well as the correlation between the melt's superheating and supercooling has been studied by the DTA method. Some additional endothermic effects above the melting point or liquidus temperature were observed in all the investigated melts. A high degree of structural ordering both in the pure and doped melts was concluded. The structure of the molten state is determined by the thermal pre-history of the solid one. The possibility of a high-temperature CdTe polymorphic modification is discussed.

  20. Effect of Melting Point on the Physical Properties of Anhydrous Milk Fat

    Science.gov (United States)

    Wang, Yunna; Li, Yang; Han, Jie; Li, Yan; Zhang, Liebing

    2017-12-01

    The effect of melting point on the physical properties of anhydrous milk fat were investigated. The results showed that high melting fractions (HMF) (S30,S35) were enriched in long-chain fatty acids, whereas low melting fractions (LMF)(S5,S10,S15) were enriched in short-chain and unsaturated fatty acids. From S5 to S35, enthalpy value was gradually increased on both crystallization and melting condition, so as SFC on different temperature. The mixture and chemical interesterification allowed obtaining fats with various degrees of plasticity, increasing the possibilities for the commercial use of different fraction of AMF.

  1. Prevention of leakage of low-melting-point metals from styrofoam molds.

    Science.gov (United States)

    Herman, M W; Robinson, A; Small, R C

    1975-10-01

    Leakage of low-melting-point metals from the underside of polystyrene molds can be prevented by applying a silicone caulking material to the bottom of the mold and pressing the mold on a metal plate before pouring.

  2. Origin of melting point depression for rare gas solids confined in carbon pores.

    Science.gov (United States)

    Morishige, Kunimitsu; Kataoka, Takaaki

    2015-07-21

    To obtain insights into the mechanism of the melting-point depression of rare gas solids confined in crystalline carbon pores, we examined the freezing and melting behavior of Xe and Ar confined to the crystalline pores of ordered mesoporous carbons as well as compressed exfoliated graphite compared to the amorphous pores of ordered mesoporous silicas, by means of X-ray diffraction. For the Xe and Ar confined to the crystalline carbon pores, there was no appreciable thermal hysteresis between freezing and melting. Furthermore, the position of the main diffraction peak did not change appreciably on freezing and melting. This strongly suggests that the liquids confined in the carbon pores form a multilayered structure parallel to the smooth walls. For the Xe and Ar confined to the amorphous silica pores, on the other hand, the position of the main diffraction peak shifted into higher scattering angle on freezing suggested that the density of the confined solid is distinctly larger than for the confined liquid. Using compressed exfoliated graphite with carbon walls of higher crystallinity, we observed that three-dimensional (3D) microcrystals of Xe confined in the slit-shaped pores melted to leave the unmelted bilayers on the pore walls below the bulk triple point. The lattice spacing of the 3D microcrystals confined is larger by ∼0.7% than that of the bilayer next to the pore walls in the vicinity of the melting point.

  3. Origin of melting point depression for rare gas solids confined in carbon pores

    International Nuclear Information System (INIS)

    Morishige, Kunimitsu; Kataoka, Takaaki

    2015-01-01

    To obtain insights into the mechanism of the melting-point depression of rare gas solids confined in crystalline carbon pores, we examined the freezing and melting behavior of Xe and Ar confined to the crystalline pores of ordered mesoporous carbons as well as compressed exfoliated graphite compared to the amorphous pores of ordered mesoporous silicas, by means of X-ray diffraction. For the Xe and Ar confined to the crystalline carbon pores, there was no appreciable thermal hysteresis between freezing and melting. Furthermore, the position of the main diffraction peak did not change appreciably on freezing and melting. This strongly suggests that the liquids confined in the carbon pores form a multilayered structure parallel to the smooth walls. For the Xe and Ar confined to the amorphous silica pores, on the other hand, the position of the main diffraction peak shifted into higher scattering angle on freezing suggested that the density of the confined solid is distinctly larger than for the confined liquid. Using compressed exfoliated graphite with carbon walls of higher crystallinity, we observed that three-dimensional (3D) microcrystals of Xe confined in the slit-shaped pores melted to leave the unmelted bilayers on the pore walls below the bulk triple point. The lattice spacing of the 3D microcrystals confined is larger by ∼0.7% than that of the bilayer next to the pore walls in the vicinity of the melting point

  4. Estimating the physicochemical properties of polyhalogenated aromatic and aliphatic compounds using UPPER: part 1. Boiling point and melting point.

    Science.gov (United States)

    Admire, Brittany; Lian, Bo; Yalkowsky, Samuel H

    2015-01-01

    The UPPER (Unified Physicochemical Property Estimation Relationships) model uses enthalpic and entropic parameters to estimate 20 biologically relevant properties of organic compounds. The model has been validated by Lian and Yalkowsky on a data set of 700 hydrocarbons. The aim of this work is to expand the UPPER model to estimate the boiling and melting points of polyhalogenated compounds. In this work, 19 new group descriptors are defined and used to predict the transition temperatures of an additional 1288 compounds. The boiling points of 808 and the melting points of 742 polyhalogenated compounds are predicted with average absolute errors of 13.56 K and 25.85 K, respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Ultra-dense energy storage utilizing high melting point metallic alloys and photovoltaic cells

    OpenAIRE

    Datas Medina, Alejandro; Martí Vega, Antonio; Cañizo Nadal, Carlos del; Luque López, Antonio

    2015-01-01

    A novel concept for energy storage utilizing high melting point metallic alloys and photovoltaic cells is presented. In the proposed system, the energy is stored in the form of latent heat of metallic alloys and converted to electricity upon demand by infrared sensitive photovoltaic cells. Silicon is considered in this paper due to its extremely high latent heat (1800 J/g), melting point (1410ºC), low cost (~$1.7/kg) and abundance on earth. The proposed solution enables an enormous energy sto...

  6. Preparation of 147Pm metal and the determination of the melting point and phase transformation temperatures

    International Nuclear Information System (INIS)

    Angelini, P.; Adair, H.L.

    1976-07-01

    The promethium metal used in the determination of the melting point and phase transformation temperatures was prepared by reduction of promethium oxide with thorium metal at 1600 0 C and distilling the promethium metal into a quartz dome. The melting point and phase transformation temperatures of promethium metal were found to be 1042 +- 5 0 C and 890 +- 5 0 C, respectively. The ratio for the heat of the high-temperature transformation to the heat of fusion was determined to be 0.415

  7. A density functional theory based approach for predicting melting points of ionic liquids.

    Science.gov (United States)

    Chen, Lihua; Bryantsev, Vyacheslav S

    2017-02-01

    Accurate prediction of melting points of ILs is important both from the fundamental point of view and from the practical perspective for screening ILs with low melting points and broadening their utilization in a wider temperature range. In this work, we present an ab initio approach to calculate melting points of ILs with known crystal structures and illustrate its application for a series of 11 ILs containing imidazolium/pyrrolidinium cations and halide/polyatomic fluoro-containing anions. The melting point is determined as a temperature at which the Gibbs free energy of fusion is zero. The Gibbs free energy of fusion can be expressed through the use of the Born-Fajans-Haber cycle via the lattice free energy of forming a solid IL from gaseous phase ions and the sum of the solvation free energies of ions comprising IL. Dispersion-corrected density functional theory (DFT) involving (semi)local (PBE-D3) and hybrid exchange-correlation (HSE06-D3) functionals is applied to estimate the lattice enthalpy, entropy, and free energy. The ions solvation free energies are calculated with the SMD-generic-IL solvation model at the M06-2X/6-31+G(d) level of theory under standard conditions. The melting points of ILs computed with the HSE06-D3 functional are in good agreement with the experimental data, with a mean absolute error of 30.5 K and a mean relative error of 8.5%. The model is capable of accurately reproducing the trends in melting points upon variation of alkyl substituents in organic cations and replacement one anion by another. The results verify that the lattice energies of ILs containing polyatomic fluoro-containing anions can be approximated reasonably well using the volume-based thermodynamic approach. However, there is no correlation of the computed lattice energies with molecular volume for ILs containing halide anions. Moreover, entropies of solid ILs follow two different linear relationships with molecular volume for halides and polyatomic fluoro

  8. Melting point gram-atomic volumes and enthalpies of atomization for liquid elements

    International Nuclear Information System (INIS)

    Lamoreaux, R.H.

    1976-01-01

    Values of the gram-atomic volumes and enthalpies of atomization to the monatomic ideal gas state for liquid elements at their melting points are collected to facilitate predictions of the behavior of mixed systems. Estimated values are given for experimentally undetermined quantities

  9. Estimating the melting point, entropy of fusion, and enthalpy of fusion of organic compounds via SPARC

    Science.gov (United States)

    The entropies of fusion, enthalies of fusion, and melting points of organic compounds can be estimated through three models developed using the SPARC (SPARC Performs Automated Reasoning in Chemistry) platform. The entropy of fusion is modeled through a combination of interaction ...

  10. The Relationship between Lattice Enthalpy and Melting Point in Magnesium and Aluminium Oxides. Science Notes

    Science.gov (United States)

    Talbot, Christopher; Yap, Lydia

    2013-01-01

    This "Science Note" presents a study by Christopher Talbot and Lydia Yap, who teach IB Chemistry at Anglo-Chinese School (Independent), Republic of Singapore, to pre-university students. Pre-university students may postulate the correlation between the magnitude of the lattice enthalpy compound and its melting point, since both…

  11. Predicting Melting Points of Organic Molecules: Applications to Aqueous Solubility Prediction Using the General Solubility Equation.

    Science.gov (United States)

    McDonagh, J L; van Mourik, T; Mitchell, J B O

    2015-11-01

    In this work we make predictions of several important molecular properties of academic and industrial importance to seek answers to two questions: 1) Can we apply efficient machine learning techniques, using inexpensive descriptors, to predict melting points to a reasonable level of accuracy? 2) Can values of this level of accuracy be usefully applied to predicting aqueous solubility? We present predictions of melting points made by several novel machine learning models, previously applied to solubility prediction. Additionally, we make predictions of solubility via the General Solubility Equation (GSE) and monitor the impact of varying the logP prediction model (AlogP and XlogP) on the GSE. We note that the machine learning models presented, using a modest number of 2D descriptors, can make melting point predictions in line with the current state of the art prediction methods (RMSE≥40 °C). We also find that predicted melting points, with an RMSE of tens of degrees Celsius, can be usefully applied to the GSE to yield accurate solubility predictions (log10 S RMSE<1) over a small dataset of drug-like molecules. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Morphological factor in the melting point depression of polypropylene by alkanes

    Czech Academy of Sciences Publication Activity Database

    Šimek, L.; Dostál, J.; Bohdanecký, Miloslav

    2001-01-01

    Roč. 42, č. 21 (2001), s. 8897-8900 ISSN 0032-3861 R&D Projects: GA AV ČR KSK4050111 Institutional research plan: CEZ:AV0Z4050913 Keywords : isotactic polypropylene * n-alkanes * melting point depression Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.681, year: 2001

  13. Models for mean bonding length, melting point and lattice thermal expansion of nanoparticle materials

    Energy Technology Data Exchange (ETDEWEB)

    Omar, M.S., E-mail: dr_m_s_omar@yahoo.com [Department of Physics, College of Science, University of Salahaddin-Erbil, Arbil, Kurdistan (Iraq)

    2012-11-15

    Graphical abstract: Three models are derived to explain the nanoparticles size dependence of mean bonding length, melting temperature and lattice thermal expansion applied on Sn, Si and Au. The following figures are shown as an example for Sn nanoparticles indicates hilly applicable models for nanoparticles radius larger than 3 nm. Highlights: ► A model for a size dependent mean bonding length is derived. ► The size dependent melting point of nanoparticles is modified. ► The bulk model for lattice thermal expansion is successfully used on nanoparticles. -- Abstract: A model, based on the ratio number of surface atoms to that of its internal, is derived to calculate the size dependence of lattice volume of nanoscaled materials. The model is applied to Si, Sn and Au nanoparticles. For Si, that the lattice volume is increases from 20 Å{sup 3} for bulk to 57 Å{sup 3} for a 2 nm size nanocrystals. A model, for calculating melting point of nanoscaled materials, is modified by considering the effect of lattice volume. A good approach of calculating size-dependent melting point begins from the bulk state down to about 2 nm diameter nanoparticle. Both values of lattice volume and melting point obtained for nanosized materials are used to calculate lattice thermal expansion by using a formula applicable for tetrahedral semiconductors. Results for Si, change from 3.7 × 10{sup −6} K{sup −1} for a bulk crystal down to a minimum value of 0.1 × 10{sup −6} K{sup −1} for a 6 nm diameter nanoparticle.

  14. Models for mean bonding length, melting point and lattice thermal expansion of nanoparticle materials

    International Nuclear Information System (INIS)

    Omar, M.S.

    2012-01-01

    Graphical abstract: Three models are derived to explain the nanoparticles size dependence of mean bonding length, melting temperature and lattice thermal expansion applied on Sn, Si and Au. The following figures are shown as an example for Sn nanoparticles indicates hilly applicable models for nanoparticles radius larger than 3 nm. Highlights: ► A model for a size dependent mean bonding length is derived. ► The size dependent melting point of nanoparticles is modified. ► The bulk model for lattice thermal expansion is successfully used on nanoparticles. -- Abstract: A model, based on the ratio number of surface atoms to that of its internal, is derived to calculate the size dependence of lattice volume of nanoscaled materials. The model is applied to Si, Sn and Au nanoparticles. For Si, that the lattice volume is increases from 20 Å 3 for bulk to 57 Å 3 for a 2 nm size nanocrystals. A model, for calculating melting point of nanoscaled materials, is modified by considering the effect of lattice volume. A good approach of calculating size-dependent melting point begins from the bulk state down to about 2 nm diameter nanoparticle. Both values of lattice volume and melting point obtained for nanosized materials are used to calculate lattice thermal expansion by using a formula applicable for tetrahedral semiconductors. Results for Si, change from 3.7 × 10 −6 K −1 for a bulk crystal down to a minimum value of 0.1 × 10 −6 K −1 for a 6 nm diameter nanoparticle.

  15. New Approach in Filling of Fixed-Point Cells: Case Study of the Melting Point of Gallium

    Science.gov (United States)

    Bojkovski, J.; Hiti, M.; Batagelj, V.; Drnovšek, J.

    2008-02-01

    The typical way of constructing fixed-point cells is very well described in the literature. The crucible is loaded with shot, or any other shape of pure metal, inside an argon-filled glove box. Then, the crucible is carefully slid into a fused-silica tube that is closed at the top with an appropriate cap. After that, the cell is removed from the argon glove box and melted inside a furnace while under vacuum or filled with an inert gas like argon. Since the metal comes as shot, or in some other shape such as rods of various sizes, and takes more volume than the melted material, it is necessary to repeat the procedure until a sufficient amount of material is introduced into the crucible. With such a procedure, there is the possibility of introducing additional impurities into the pure metal with each cycle of melting the material and putting it back into the glove box to fill the cell. Our new approach includes the use of a special, so-called dry-box system, which is well known in chemistry. The atmosphere inside the dry box contains less than 20 ppm of water and less than 3 ppm of oxygen. Also, the size of the dry box allows it to contain a furnace for melting materials, not only for gallium but for higher-temperature materials as well. With such an approach, the cell and all its parts (pure metal, graphite, fused-silica tube, and cap) are constantly inside the controlled atmosphere, even while melting the material and filling the crucible. With such a method, the possibility of contaminating the cell during the filling process is minimized.

  16. Degradation mechanism and thermal stability of urea nitrate below the melting point

    International Nuclear Information System (INIS)

    Desilets, Sylvain; Brousseau, Patrick; Chamberland, Daniel; Singh, Shanti; Feng, Hongtu; Turcotte, Richard; Anderson, John

    2011-01-01

    Highlights: → Decomposition mechanism of urea nitrate. → Spectral characterization of the decomposition mechanism. → Thermal stability of urea nitrate at 50, 70 and 100 o C. → Chemical balance of decomposed products released. - Abstract: Aging and degradation of urea nitrate below the melting point, at 100 o C, was studied by using thermal analysis and spectroscopic methods including IR, Raman, 1 H and 13 C NMR techniques. It was found that urea nitrate was completely degraded after 72 h at 100 o C into a mixture of solids (69%) and released gaseous species (31%). The degradation mechanism below the melting point was clearly identified. The remaining solid mixture was composed of ammonium nitrate, urea and biuret while unreacted residual nitric and isocyanic acids as well as traces of ammonia were released as gaseous species at 100 o C. The thermal stability of urea nitrate, under extreme storage conditions (50 o C), was also examined by isothermal nano-calorimetry.

  17. Determination of melting point of vegetable oils and fats by differential scanning calorimetry (DSC technique.

    Directory of Open Access Journals (Sweden)

    Nassu, Renata Tieko

    1999-02-01

    Full Text Available Melting point of fats is used to characterize oils and fats and is related to their physical properties, such as hardness and thermal behaviour. The present work shows the utilization of DSC technique on the determination of melting point of fats. In a comparison with softening point (AOCS method Cc 3-25, DSC values were higher than those obtained by AOCS method. It has occurred due to the fact that values obtained by DSC technique were taken when the fat had melted completely. DSC was also useful for determining melting point of liquid oils, such as soybean and cottonseed ones.

    El punto de fusión de grasas es usado para caracterizar aceites y grasas, y está relacionado con sus propiedades físicas, tales como dureza y comportamiento térmico. El presente trabajo muestra la utilización de la técnica de Calorimetría Diferencial de Barrido (DSC en la determinación del punto de fusión de grasas. En comparación con el punto de ablandamiento (AOCS método Cc 3-25, los valores de DSC fueron más altos que los obtenidos por los métodos de AOCS. Esto ha ocurrido debido al hecho que los valores obtenidos por la técnica de DSC fueron tomados cuando la grasa había fundido completamente. DSC fue también útil para determinar puntos de fusión de aceites líquidos, tales como los de soya y algodón.

  18. Draft report on melt point as a function of composition for urania-based systems

    Energy Technology Data Exchange (ETDEWEB)

    Valdez, James A [Los Alamos National Laboratory; Byler, Darrin D [Los Alamos National Laboratory

    2012-06-08

    This report documents the testing of a urania (UO{sub 2.00}) sample as a baseline and the attempt to determine the melt point associated with 4 compositions of urania-ceria and urania-neodymia pseudo binaries provided by ORNL, with compositions of 95/5, and 80/20 and of (U/Ce)O{sub 2.00} and (U/Nd)O{sub 2.00} in the newly developed ceramic melt point determination system. A redesign of the system using parts fabricated from tungsten was undertaken in order to help prevent contamination and tungsten carbide formation in the crucibles. The previously developed system employed mostly graphite parts that were shown to react with the sample containment black-body crucible leading to unstable temperature readings and crucible failure, thus the redesign. Measured melt point values of UO{sub 2.00} and U{sub 0.95}Ce{sub 0.05}O{sub 2.00}, U{sub 0.80}Ce{sub 0.20}O{sub 2.00}, U{sub 0.95}Nd{sub 0.05}O{sub 2.00} and U{sub 0.80}Nd{sub 0.20}O{sub 2.00} were measured using a 2-color pyrometer. The value measured for UO{sub 2.00} was consistent with the published accepted value 2845 C {+-} 25 C, although a wide range of values has been published by researchers and will be discussed later in the text. For comparison, values obtained from a published binary phase diagram of UO{sub 2}-Nd{sub 2}O{sub 3} were used for comparison with our measure values. No literature melt point values for comparison with the measurements performed in this study were found for (U/Ce)O{sub 2.00} in our stoichiometry range.

  19. Vapor Pressure Data Analysis and Correlation Methodology for Data Spanning the Melting Point

    Science.gov (United States)

    2013-10-01

    specimen is adequately degassed, the liquid menisci in the U-tube are brought to the same level and the pressure read on the manometer . The measurement...VAPOR PRESSURE DATA ANALYSIS AND CORRELATION METHODOLOGY FOR DATA SPANNING THE MELTING POINT ECBC-CR-135 David E...REPORT TYPE Final 3. DATES COVERED (From - To) Mar 2013 - June 2013 4. TITLE AND SUBTITLE Vapor Pressure Data Analysis and Correlation Methodology

  20. 46 CFR 153.488 - Design and equipment for tanks carrying high melting point NLSs: Category B.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Design and equipment for tanks carrying high melting... HAZARDOUS MATERIALS Design and Equipment Design and Equipment for Pollution Control § 153.488 Design and equipment for tanks carrying high melting point NLSs: Category B. Unless waived under § 153.491, for a ship...

  1. The role of hydrogen bonds in the melting points of sulfonate-based protic organic salts

    DEFF Research Database (Denmark)

    Luo, Jiangshui

    2016-01-01

    there is evidence of bond formation [6]. Hydrogen bonds in the solid state fall into the classification of strong, moderate, and weak hydrogen bonds [7]. In molecular systems like H2O (vs. H2S) or NH3 (vs. PH3), strong hydrogen bonds lead to higher melting points. However, in organic salts, the situation may......There are three main types of interactions inside organic salts - electrostatic interaction, hydrogen bonding and van der Waals force [1-4]. While van der Waals force is relatively weak, it is hydrogen bonding and particularly electrostatic interaction that determine the lattice energies of ionic...

  2. Micro- and nano-spheres of low melting point metals and alloys, formed by ultrasonic cavitation.

    Science.gov (United States)

    Friedman, H; Reich, S; Popovitz-Biro, R; von Huth, P; Halevy, I; Koltypin, Y; Gedanken, A; Porat, Z

    2013-01-01

    Metals and alloys of low melting points (metals into microspheres that solidify rapidly upon cooling. This method has been applied to seven pure metals (Ga, In, Sn, Bi, Pb, Zn, Hg) and two eutectic alloys of gold (Au-Ge and Au-Si). The morphology and composition of the resulting microspheres were examined by SEM and EDS. Eutectic Au-Si formed also crystalline Au nanoparticles, which were separated and studied by HRTEM. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Degradation mechanism and thermal stability of urea nitrate below the melting point

    Energy Technology Data Exchange (ETDEWEB)

    Desilets, Sylvain, E-mail: sylvain.desilets@drdc-rddc.gc.ca [Defence R and D Canada, Valcartier, 2459 Pie-XI Blvd North, Val-Belair, Quebec, Canada G3J 1X5 (Canada); Brousseau, Patrick; Chamberland, Daniel [Defence R and D Canada, Valcartier, 2459 Pie-XI Blvd North, Val-Belair, Quebec, Canada G3J 1X5 (Canada); Singh, Shanti; Feng, Hongtu; Turcotte, Richard [Canadian Explosives Research Laboratory, 1 Haanel Dr. Ottawa, Quebec, Canada K1A 1M1 (Canada); Anderson, John [Defence R and D Canada, Suffield, Box 4000, stn Main, Medicine Hat, Alberta, Canada T1A 8K6 (Canada)

    2011-07-10

    Highlights: {yields} Decomposition mechanism of urea nitrate. {yields} Spectral characterization of the decomposition mechanism. {yields} Thermal stability of urea nitrate at 50, 70 and 100 {sup o}C. {yields} Chemical balance of decomposed products released. - Abstract: Aging and degradation of urea nitrate below the melting point, at 100 {sup o}C, was studied by using thermal analysis and spectroscopic methods including IR, Raman, {sup 1}H and {sup 13}C NMR techniques. It was found that urea nitrate was completely degraded after 72 h at 100 {sup o}C into a mixture of solids (69%) and released gaseous species (31%). The degradation mechanism below the melting point was clearly identified. The remaining solid mixture was composed of ammonium nitrate, urea and biuret while unreacted residual nitric and isocyanic acids as well as traces of ammonia were released as gaseous species at 100 {sup o}C. The thermal stability of urea nitrate, under extreme storage conditions (50 {sup o}C), was also examined by isothermal nano-calorimetry.

  4. Mixing and electronic entropy contributions to thermal energy storage in low melting point alloys

    Science.gov (United States)

    Shamberger, Patrick J.; Mizuno, Yasushi; Talapatra, Anjana A.

    2017-07-01

    Melting of crystalline solids is associated with an increase in entropy due to an increase in configurational, rotational, and other degrees of freedom of a system. However, the magnitude of chemical mixing and electronic degrees of freedom, two significant contributions to the entropy of fusion, remain poorly constrained, even in simple 2 and 3 component systems. Here, we present experimentally measured entropies of fusion in the Sn-Pb-Bi and In-Sn-Bi ternary systems, and decouple mixing and electronic contributions. We demonstrate that electronic effects remain the dominant contribution to the entropy of fusion in multi-component post-transition metal and metalloid systems, and that excess entropy of mixing terms can be equal in magnitude to ideal mixing terms, causing regular solution approximations to be inadequate in the general case. Finally, we explore binary eutectic systems using mature thermodynamic databases, identifying eutectics containing at least one semiconducting intermetallic phase as promising candidates to exceed the entropy of fusion of monatomic endmembers, while simultaneously maintaining low melting points. These results have significant implications for engineering high-thermal conductivity metallic phase change materials to store thermal energy.

  5. Melting heat transfer in stagnation point flow of carbon nanotubes towards variable thickness surface

    Directory of Open Access Journals (Sweden)

    T. Hayat

    2016-01-01

    Full Text Available This work concentrates on the mathematical modeling for stagnation point flow of nanofluids over an impermeable stretching sheet with variable thickness. Carbon nanotubes [single-wall carbon nanotubes (SWCNTs and multi-wall carbon nanotubes (MWCNTs] as the nanoparticles are utilized. Water and kerosene oil are taken as the base fluids. Heat transfer through melting effect is discussed. Transformation procedure is adapted to obtain the non-linear ordinary differential equations from the fundamental laws of mass, linear momentum and energy. The optimal values of convergence control parameters and corresponding individual and total residual errors for SWCNTs and MWCNTs are computed by means of homotopy analysis method (HAM based BVPh 2.0. Characteristics of different involved parameters on the velocity, temperature, skin friction coefficient and Nusselt number are discussed. Higher velocity profile is observed for wall thickness parameter in case of water carbon nanotubes when compared with the kerosene oil carbon nanotubes.

  6. The effect of sire breed on the melting point and fatty acid composition of subcutaneous fat in steers.

    Science.gov (United States)

    Perry, D; Nicholls, P J; Thompson, J M

    1998-01-01

    Fatty acid composition and the melting point of subcutaneous fat was determined in 18 Hereford, 25 Brahman x Hereford, 22 Simmental x Hereford, and 15 Friesian x Hereford steers that were grown out on pasture at two sites and slaughtered when the mean weight of the Herefords at each site was ca. 450 kg. Multivariate and univariate analyses tested the relations of fatty acid composition, degree of saturation, and melting point with sire breed, environment, age, and carcass characteristics. Hereford and Brahman steers were fatter than the Simmental and Friesian steers. Fat from Brahman-sired steers had a melting point 2.5 degrees C lower than fat from the Bos taurus-sired steers at the same age and had a higher proportion of unsaturated fatty acids, independent of variation in carcass weight and fatness. Melting point and degree of saturation decreased as age increased. Step-down discriminant analyses identified a set of three acids (14:0, 16:0, and 17:1) that differed among sire breeds, independent of differences in melting point: the acids 14:0 and 16:0 discriminated between Brahman and Bos taurus steers and 17:1 between Hereford and Simmental and Friesian steers. Increase in fatness was associated with an increase in 17:1, but, at the same fatness, no acids discriminated among the Bos taurus-sired steers. The use of Bos indicus cattle or their crossbreeds in situations in which hard-setting fat is likely may mitigate the problem.

  7. Increase of Unsaturated Fatty Acids (Low Melting Point) of Broiler Fatty Waste Obtained Through Staphylococcus xylosus Fermentation.

    Science.gov (United States)

    Marques, Roger V; Duval, Eduarda H; Corrêa, Luciara B; Corrêa, Érico K

    2015-11-01

    The increasing rise in the production of meat around the world causes a significant generation of agro-industrial waste--most of it with a low value added. Fatty wastes have the potential of being converted into biodiesel, given the overcome of technological and economical barriers, as well as its presentation in solid form. Therefore, the aim of this work was to investigate the capacity of Staphylococcus xylosus strains to modify the chemical structure of chicken fatty wastes intending to reduce the melting points of the wastes to mild temperatures, thereby breaking new ground in the production of biodiesel from these sources in an economically attractive and sustainable manner. The effects in time of fermentation and concentration of the fat in the medium were investigated, assessing the melting point and profile of fatty acids. The melting temperature showed a decrease of approximately 22 °C in the best operational conditions, due to reduction in the content of saturated fatty acids (high melting point) and increase of unsaturated fatty acids (low melting point).

  8. CADASTER QSPR Models for Predictions of Melting and Boiling Points of Perfluorinated Chemicals.

    Science.gov (United States)

    Bhhatarai, Barun; Teetz, Wolfram; Liu, Tao; Öberg, Tomas; Jeliazkova, Nina; Kochev, Nikolay; Pukalov, Ognyan; Tetko, Igor V; Kovarich, Simona; Papa, Ester; Gramatica, Paola

    2011-03-14

    Quantitative structure property relationship (QSPR) studies on per- and polyfluorinated chemicals (PFCs) on melting point (MP) and boiling point (BP) are presented. The training and prediction chemicals used for developing and validating the models were selected from Syracuse PhysProp database and literatures. The available experimental data sets were split in two different ways: a) random selection on response value, and b) structural similarity verified by self-organizing-map (SOM), in order to propose reliable predictive models, developed only on the training sets and externally verified on the prediction sets. Individual linear and non-linear approaches based models developed by different CADASTER partners on 0D-2D Dragon descriptors, E-state descriptors and fragment based descriptors as well as consensus model and their predictions are presented. In addition, the predictive performance of the developed models was verified on a blind external validation set (EV-set) prepared using PERFORCE database on 15 MP and 25 BP data respectively. This database contains only long chain perfluoro-alkylated chemicals, particularly monitored by regulatory agencies like US-EPA and EU-REACH. QSPR models with internal and external validation on two different external prediction/validation sets and study of applicability-domain highlighting the robustness and high accuracy of the models are discussed. Finally, MPs for additional 303 PFCs and BPs for 271 PFCs were predicted for which experimental measurements are unknown. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Organic Crystal Engineering of Thermosetting Cyanate Ester Monomers: Influence of Structure on Melting Point

    Science.gov (United States)

    2016-05-27

    modify, reproduce, release, perform, display, or disclose the work. 14. ABSTRACT Key principles needed for the rational design of thermosetting...determination of the thermodynamic properties associated with melting showed that the substitution of silicon for the central quaternary carbon in...melting, leading to a decrease in the melting temperature of 21.8 ± 0.2 K. In contrast, the analogous silicon substitution in the tri(cyanate ester

  10. Experimental study and numerical simulation of the salinity effect on water-freezing point and ice-melting rate

    Science.gov (United States)

    Qin, N.; Wu, Y.; Wang, H. W.; Wang, Y. Y.

    2017-12-01

    In this paper, based on the background of snowmelt de-icing tools, we studied the effect of salt on freezing point and melting rate of ice through laboratory test and FLUENT numerical simulation analysis. It was confirmed that the freezing point is inversely proportional to the salt solid content, and with the salt solid content increasing, the freezing process of salt water gradually accepts the curing rule of non-crystal solids. At the same temperature, an increase in the salt solid content, the ice melting rate increase by the empirical formula linking the melting time with temperature and salt content. The theoretical aspects of solid/fluid transformation are discussed in detail.

  11. Graphene confinement effects on melting/freezing point and structure and dynamics behavior of water.

    Science.gov (United States)

    Foroutan, Masumeh; Fatemi, S Mahmood; Shokouh, F

    2016-05-01

    In this work, the melting/freezing point of confined water between two graphene sheets was calculated from the direct coexistence of the solid-liquid interface. Also, molecular dynamics simulation of confined liquid water-ice between two graphene sheets was applied. The phase transition temperature of the confined ice-water mixture was calculated as 240K that was 29K less than the non-confined ice-water system. In order to study the behavior of water molecules at different distances from the graphene sheets, 5 regions were provided using some imaginary planes, located between two graphene sheets. The obtained simulation results showed that water molecules located in the region near each graphene sheet with the thickness of 2nm had a different behavior from other water molecules located in other regions. The results demonstrated that water molecules in the vicinity of graphene sheets had more mean square displacements than those in the middle regions. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Temperature calibration procedure for thin film substrates for thermo-ellipsometric analysis using melting point standards

    Energy Technology Data Exchange (ETDEWEB)

    Kappert, Emiel J.; Raaijmakers, Michiel J.T.; Ogieglo, Wojciech; Nijmeijer, Arian; Huiskes, Cindy; Benes, Nieck E., E-mail: n.e.benes@utwente.nl

    2015-02-10

    Highlights: • Facile temperature calibration method for thermo-ellipsometric analysis. • The melting point of thin films of indium, lead, zinc, and water can be detected by ellipsometry. • In-situ calibration of ellipsometry hot stage, without using any external equipment. • High-accuracy temperature calibration (±1.3 °C). - Abstract: Precise and accurate temperature control is pertinent to studying thermally activated processes in thin films. Here, we present a calibration method for the substrate–film interface temperature using spectroscopic ellipsometry. The method is adapted from temperature calibration methods that are well developed for thermogravimetric analysis and differential scanning calorimetry instruments, and is based on probing a transition temperature. Indium, lead, and zinc could be spread on a substrate, and the phase transition of these metals could be detected by a change in the Ψ signal of the ellipsometer. For water, the phase transition could be detected by a loss of signal intensity as a result of light scattering by the ice crystals. The combined approach allowed for construction of a linear calibration curve with an accuracy of 1.3 °C or lower over the full temperature range.

  13. Characterization of the shear test method with low melting point In-48Sn solder joints

    International Nuclear Information System (INIS)

    Kim, Jong-Woong; Jung, Seung-Boo

    2005-01-01

    The ball shear tests were investigated in terms of effects of test parameters, i.e. shear height and shear speed, with an experimental and non-linear finite element analysis for evaluating the solder joint integrity of area array packages. A representative low melting point solder, In-48Sn, was examined in this work. The substrate was a common solder mask defined (SMD) type with solder bond pad openings of 460 μm in diameter. The microstructural investigations were carried out using scanning electron microscopy (SEM), and the intermetallic compounds (IMCs) were identified with energy dispersive spectrometer (EDS) and electron probe micro analyzer (EPMA). Shear tests were conducted with the two varying test parameters. It could be observed that increasing shear height, at fixed shear speed, has the effect of decreasing shear force, while the shear force increased with increasing shear speed at fixed shear height. Too high shear height could cause some bad effects on the test results such as unexpected high standard deviation values or shear tip sliding from the solder ball surface. The low shear height conditions were favorable for screening the type of brittle interfacial fractures or the degraded layers in the interfaces. The sensitivity of shear speed in In-48Sn solder is largely higher than those of Sn-based solders

  14. Investigation of the Melting Point Depression of 12-Hydroxystearic Acid Organogels Using the Flory Diluent Model

    Science.gov (United States)

    Cavicchi, Kevin; Lipowski, Brian

    2013-03-01

    This talk will focus on the gelation behavior of 12-hydroxystearic acid (12-HSA) in organic solvents. Thermo-reversible gelation occurs by crystallization of 12-HSA in organic solvent to form 3-D fibrillar networks. The melting point vs. composition for 12-HSA in a range of solvents has been measured. The liquidus lines could be fit with the Flory-diluent model that takes into account the non-ideal free energy of mixing and the disparity in the size of the solvent and 12-HSA molecules. The fits indicated that the effective molar volume of 12-HSA increased as the hydrogen bonding Hansen solubility parameter δh of the solvent decreased. This is attributed to the hydrogen-bonding driven aggregation of the 12-HSA in the liquid state based on previous observations that 12-HSA forms aggregated structures in non-polar solvents (e.g. dimers and tetrameters). These results indicate that the stabilization of the solid phase in 12-HSA solutions has contributions from both variations in the entropy of mixing as well the enthalpy of mixing. The importance of both these factors for designing small molecule gelators will be discussed.

  15. Point, surface and volumetric heat sources in the thermal modelling of selective laser melting

    Science.gov (United States)

    Yang, Yabin; Ayas, Can

    2017-10-01

    Selective laser melting (SLM) is a powder based additive manufacturing technique suitable for producing high precision metal parts. However, distortions and residual stresses within products arise during SLM because of the high temperature gradients created by the laser heating. Residual stresses limit the load resistance of the product and may even lead to fracture during the built process. It is therefore of paramount importance to predict the level of part distortion and residual stress as a function of SLM process parameters which requires a reliable thermal modelling of the SLM process. Consequently, a key question arises which is how to describe the laser source appropriately. Reasonable simplification of the laser representation is crucial for the computational efficiency of the thermal model of the SLM process. In this paper, first a semi-analytical thermal modelling approach is described. Subsequently, the laser heating is modelled using point, surface and volumetric sources, in order to compare the influence of different laser source geometries on the thermal history prediction of the thermal model. The present work provides guidelines on appropriate representation of the laser source in the thermal modelling of the SLM process.

  16. New encapsulation method using low-melting-point alloy for sealing micro heat pipes

    International Nuclear Information System (INIS)

    Li, Congming; Wang, Xiaodong; Zhou, Chuanpeng; Luo, Yi; Li, Zhixin; Li, Sidi

    2017-01-01

    This study proposed a method using Low-melting-point alloy (LMPA) to seal Micro heat pipes (MHPs), which were made of Si substrates and glass covers. Corresponding MHP structures with charging and sealing channels were designed. Three different auxiliary structures were investigated to study the sealability of MHPs with LMPA. One structure is rectangular and the others are triangular with corner angles of 30° and 45°, respectively. Each auxiliary channel for LMPA is 0.5 mm wide and 135 μm deep. LMPA was heated to molten state, injected to channels, and then cooled to room temperature. According to the material characteristic of LMPA, the alloy should swell in the following 12 hours to form strong interaction force between LMPA and Si walls. Experimental results show that the flow speed of liquid LMPA in channels plays an important role in sealing MHPs, and the sealing performance of triangular structures is always better than that of rectangular structure. Therefore, triangular structures are more suitable in sealing MHPs than rectangular ones. LMPA sealing is a plane packaging method that can be applied in the thermal management of high-power IC device and LEDs. Meanwhile, implanting in commercialized fabrication of MHP is easy.

  17. New encapsulation method using low-melting-point alloy for sealing micro heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Congming; Wang, Xiaodong; Zhou, Chuanpeng; Luo, Yi; Li, Zhixin; Li, Sidi [Dalian University of Technology, Dalian (China)

    2017-06-15

    This study proposed a method using Low-melting-point alloy (LMPA) to seal Micro heat pipes (MHPs), which were made of Si substrates and glass covers. Corresponding MHP structures with charging and sealing channels were designed. Three different auxiliary structures were investigated to study the sealability of MHPs with LMPA. One structure is rectangular and the others are triangular with corner angles of 30° and 45°, respectively. Each auxiliary channel for LMPA is 0.5 mm wide and 135 μm deep. LMPA was heated to molten state, injected to channels, and then cooled to room temperature. According to the material characteristic of LMPA, the alloy should swell in the following 12 hours to form strong interaction force between LMPA and Si walls. Experimental results show that the flow speed of liquid LMPA in channels plays an important role in sealing MHPs, and the sealing performance of triangular structures is always better than that of rectangular structure. Therefore, triangular structures are more suitable in sealing MHPs than rectangular ones. LMPA sealing is a plane packaging method that can be applied in the thermal management of high-power IC device and LEDs. Meanwhile, implanting in commercialized fabrication of MHP is easy.

  18. Removal of oxides from alkali metal melts by reductive titration to electrical resistance-change end points

    Science.gov (United States)

    Tsang, Floris Y.

    1980-01-01

    Alkali metal oxides dissolved in alkali metal melts are reduced with soluble metals which are converted to insoluble oxides. The end points of the reduction is detected as an increase in electrical resistance across an alkali metal ion-conductive membrane interposed between the oxide-containing melt and a material capable of accepting the alkali metal ions from the membrane when a difference in electrical potential, of the appropriate polarity, is established across it. The resistance increase results from blocking of the membrane face by ions of the excess reductant metal, to which the membrane is essentially non-conductive.

  19. Fabrication and Optimization of a PAGATA Gel Dosimeter: Increasing the Melting Point of the PAGAT Gel Dosimeter with Agarose Additive

    Directory of Open Access Journals (Sweden)

    Bakhtiar Azadbakht

    2010-12-01

    Full Text Available Introduction: The PAGAT polymer gel dosimeter melts at 30 ˚C and even at room temperature during the summer, so it needs to be kept in a cool place such as a refrigerator. To increase the stability of the PAGAT gel, different amounts of agarose were added to the PAGAT gel composition and the PAGATA gel was manufactured. Material and Methods: The PAGATA gel vials were irradiated using a Co-60 machine. Then, the samples were evaluated using a 1.5 T Siemens MRI scanner. The ingredients of the PAGATA normoxic gel dosimeter were 4.5% N-N' methylen-bis-acrylamide, 4.5% acrylamide, 4.5% gelatine, 5 mM tetrakis (THPC, 0.01 mM hydroquinone (HQ, 0.5% agarose and 86% de-ionized water (HPLC. Results: Melting point and sensitivity of the PAGAT gel dosimeter with addition of 0.0, 0.3, 0.5, 1.0, 1.5 and 2.0% of agarose were measured, in which the melting points were increased to 30, 82, 86, 88, 89 and 90°C and their sensitivities found to be 0.113, 0.1059, 0.125, 0.122, 0.115 and 0.2  respectively. Discussion and Conclusions: Adding agarose increased the sensitivity and background R2 of the evaluated samples. The optimum amount of agarose was found to be 0.5% regarding these parameters and also the melting point of the gel dosimeter. A value of 0.5% agarose was found to be an optimum value considering the increase of sensitivity to 0.125 and melting point to 86°C but at the expense of increasing the background R2 to 4.530.

  20. Determination of the melting point of amorphous semiconductors from the kinetics of their self-sustaining crystallization

    International Nuclear Information System (INIS)

    Kulyasova, O.A.; Balandin, V.Yu.; Dvurechenskii, A.V.; Aleksandrov, L.N.

    1987-01-01

    Amorphous semiconductors are becoming increasingly important. For this reason it is necessary to study their properties thoroughly. It is well known that the melting of amorphous semiconductors, in particular silicon (a-Si), is a first-order phase transition, occurring at a definite melting point T A that depends on the structural state of the a-Si. As was shown previously, the process of lateral self-sustaining crystallization (SC), characteristic for amorphous layers of silicon, depends on the time and temperature of the preheating, during which the layer remains amorphous but undergoes local structural changes. The purpose of this work is to determine the dependence of the depth of crystallization owing to SC in a-Si on its melting temperature. This will make it possible to determine, under experimental conditions, the value of T A from the depth of crystallization of a-Si

  1. Distributed Point Source Volcanism: A Mechanism for `Regional Plains' Resurfacing, Venus

    Science.gov (United States)

    Hansen, V. L.; Bleamaster, L. F., III

    2002-03-01

    V23/24 hosts shields that form a thin porous layer across >10x106 km2; variations in thermal gradient/conductivity, radioactive content/distribution, and surface T can result in time transgressive, incipient shallow point-source partial melting.

  2. Progress of HDDR NdFeB powders modulated by the diffusion of low melting point elements and their alloys

    Directory of Open Access Journals (Sweden)

    Lyu Meng

    2017-12-01

    Full Text Available The hydrogenation-disproportionation-desorption-recombination (HDDR process is the main technique for the fabrication of anisotropic NdFeB magnetic powder.But the intrinsic coercivity (HC of HDDR magnetic powder is low.The addition of heavy rare earth element Dy could improve its HC.It was found that the added Dy is mainly distributed in the grain boundary of HDDR magnets,which regulates grain boundary phase and increases the thickness of grain boundary to improve the anisotropy field (HA and HC of the magnets.However,Dy becomes scarcer and more expensive,which limits the practical application of HDDR magnets.To reduce the dependence on heavy rare earth elements and cost,researchers replaced the heavy rare earth element Dy by low melting point elements and their alloys through grain boundary diffusion technique.During diffusion process low melting point metal exists as liquid phase that increases the diffusion coefficient of diffusion medium as well as its contact area with grain boundary phases of HDDR magnets,and benefits its diffusion along grain boundaries and regulation of grain boundary phase.The modified grain boundary in magnets improve HC.This review paper focuses on the research progress in improving HC of HDDR NdFeB magnets by low melting point elements and their alloys.

  3. Nano-pulverization of poorly water soluble compounds with low melting points by a rotation/revolution pulverizer.

    Science.gov (United States)

    Yuminoki, K; Takeda, M; Kitamura, K; Numata, S; Kimura, K; Takatsuka, T; Hashimoto, N

    2012-08-01

    We report a method for pulverizing poorly water soluble compounds with low melting points to nanoparticles without producing an amorphous phase using a rotation/revolution pulverizer. Fenofibrate, flurbiprofen, and probucol were used as crystalline model compounds. They were suspended in a methylcellulose aqueous solution and pulverized with zirconia balls by the rotation/revolution pulverizer. Beeswax, an amorphous compound, was also examined to investigate whether nano-pulverization of a compound with a low melting point was possible. Beeswax was suspended in ethyl alcohol cooled with liquid nitrogen and pulverized with zirconia balls by the rotation/revolution pulverizer. By optimizing the pulverization parameters, nanoparticles (D50 revolution speed of 1000 rpm and a rotation/revolution ratio of 1.0 when the vessel was 0 degrees C. Amorphous fenofibrate and flurbiprofen were not detected by differential scanning calorimetry or powder X-ray diffraction, whereas small amounts of amorphous probucol were detected. Beeswax was pulverized to nanoparticles (D50 = 0.14 microm) with ethyl alcohol cooled with liquid nitrogen. Fine nanoparticles of these poorly water soluble compounds with low melting points were obtained by controlling the rotation/revolution speed and reducing the vessel temperature.

  4. Point, surface and volumetric heat sources in the thermal modelling of selective laser melting

    NARCIS (Netherlands)

    Yang, Y.; Ayas, C.; Brabazon, Dermot; Naher, Sumsun; Ul Ahad, Inam

    2017-01-01

    Selective laser melting (SLM) is a powder based additive manufacturing technique suitable for producing high precision metal parts. However, distortions and residual stresses within products arise during SLM because of the high temperature gradients created by the laser heating. Residual stresses

  5. Calculation procedure for formulating lauric and palmitic fat blends based on the grouping of triacylglycerol melting points

    International Nuclear Information System (INIS)

    Nusantoro, B.P.; Yanty, N.A.M.; Van de Walle, D.; Hidayat, C.; Danthine, S.; Dewettinck, K.

    2017-01-01

    A calculation procedure for formulating lauric and palmitic fat blends has been developed based on grouping TAG melting points. This procedure offered more flexibility in choosing the initial fats and oils and eventually gave deeper insight into the existing chemical compositions and better prediction on the physicochemical properties and microstructure of the fat blends. The amount of high, medium and low melting TAGs could be adjusted using the given calculation procedure to obtain the desired functional properties in the fat blends. Solid fat contents and melting behavior of formulated fat blends showed particular patterns with respect to ratio adjustments of the melting TAG groups. These outcomes also suggested that both TAG species and their quantity had a significant influence on the crystallization behavior of the fat blends. Palmitic fat blends, in general, were found to exhibit higher SFC values than those of Lauric fat blends. Instead of the similarity in crystal microstructure, lauric fat blends were stabilized at β polymorph while palmitic fat blends were stabilized at β’ polymorph. [es

  6. Structure and thermal expansion of Lu2O3 and Yb2O3 up to the melting points

    Science.gov (United States)

    Pavlik, Alfred; Ushakov, Sergey V.; Navrotsky, Alexandra; Benmore, Chris J.; Weber, Richard J. K.

    2017-11-01

    Knowledge of thermal expansion and high temperature phase transformations is essential for prediction and interpretation of materials behavior under the extreme conditions of high temperature and intense radiation encountered in nuclear reactors. Structure and thermal expansion of Lu2O3 and Yb2O3 were studied in oxygen and argon atmospheres up to their melting temperatures using synchrotron X-ray diffraction on laser heated levitated samples. Both oxides retained the cubic bixbyite C-type structure in oxygen and argon to melting. In contrast to fluorite-type structures, the increase in the unit cell parameter of Yb2O3 and Lu2O3 with temperature is linear within experimental error from room temperature to the melting point, with mean thermal expansion coefficients (8.5 ± 0.6) · 10-6 K-1 and (7.7 ± 0.6) · 10-6 K-1, respectively. There is no indication of a superionic (Bredig) transition in the C-type structure or of a previously suggested Yb2O3 phase transformation to hexagonal phase prior to melting.

  7. On the yield of cold and ultracold neutrons for liquid hydrogen at low temperatures near the melting point

    CERN Document Server

    Morishima, N

    1999-01-01

    The neutron scattering cross sections for liquid hydrogen in the temperature range from the melting point to the boiling point are calculated. It is shown that lowering the temperature results in a significant increase in the yield of cold neutrons: for instance, a 44% increase for an incident neutron energy of 19.4 meV. The major cause of this increment is the para-to-ortho transition of a hydrogen molecule though accompanied by an appreciable increase in the density. The results of the cold- and ultracold-neutron yields are discussed in connection with the experimental results of Altarev et al. at the WWR-M reactor.

  8. Surface Observation and Pore Size Analyses of Polypropylene/Low-Melting Point Polyester Filter Materials: Influences of Heat Treatment

    Directory of Open Access Journals (Sweden)

    Lin Jia-Horng

    2016-01-01

    Full Text Available This study proposes making filter materials with polypropylene (PP and low-melting point (LPET fibers. The influences of temperatures and times of heat treatment on the morphology of thermal bonding points and average pore size of the PP/LPET filter materials. The test results indicate that the morphology of thermal bonding points is highly correlated with the average pore size. When the temperature of heat treatment is increased, the fibers are joined first with the thermal bonding points, and then with the large thermal bonding areas, thereby decreasing the average pore size of the PP/LPET filter materials. A heat treatment of 110 °C for 60 seconds can decrease the pore size from 39.6 μm to 12.0 μm.

  9. The effect of correlated and point defects on the vortex lattice melting transition in single crystal YBa2Cu3O7-δ

    International Nuclear Information System (INIS)

    Kwok, W.K.; Fleshler, S.; Welp, U.; Downey, J.; Crabtree, G.W.; Fendrich, J. Giapintzakis, J.

    1993-08-01

    The vortex melting transition T m in several untwinned and twinned crystals measured resistively in fields up to 8 Tesla. A Lindemann criterion for vortex lattice melting is obtained in addition to a sharp hysteresis in the magnetoresistance at B m supporting a first order phase transition. The anisotropy of twin boundary pinning and its reduction of the ''kink'' in ρ(T) associated with the first order melting transition is discussed in samples with very dilute twin boundaries. We also report on direct suppression of melting transition by intrinsic pinning for H parallel ab and by electron-irradiation-induced point defects

  10. Development of high melting point, environmentally friendly solders, using the calphad approach

    DEFF Research Database (Denmark)

    Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

    2008-01-01

    An attempt has been made using the CALPHAD approach via Thermo-Calc to explore the various possible chemical compositions that adhere to the melting criterion i.e. 270-350 degrees C, required to replace the traditionally used high lead content solders for first level packaging applications. Various...... of promising solder alloy candidates. The ternary combinations that satisfied the primary solidification requirement were scrutinized taking into account the commercial interests i.e. availability, cost-effectiveness, recyclability and toxicity issues. Technical issues like manufacturability and surface...... tension have also been considered. Special focus has been given to toxicity related issues since the main ideology of looking for an alternative to high lead containing solders is not related to technical issues but due to environmental concerns....

  11. Printing low-melting-point alloy ink to directly make a solidified circuit or functional device with a heating pen

    Science.gov (United States)

    Wang, Lei; Liu, Jing

    2014-01-01

    A new method to directly print out a solidified electronic circuit through low-melting-point metal ink is proposed. A functional pen with heating capability was fabricated. Several typical thermal properties of the alloy ink Bi35In48.6Sn16Zn0.4 were measured and evaluated. Owing to the specifically selected melting point of the ink, which is slightly higher than room temperature, various electronic devices, graphics or circuits can be manufactured in a short period of time and then rapidly solidified by cooling in the surrounding air. The liquid–solid phase change mechanism of the written lines was experimentally characterized using a scanning electron microscope. In order to determine the matching substrate, wettability between the metal ink Bi35In48.6Sn16Zn0.4 and several materials, including mica plate and silicone rubber, was investigated. The resistance–temperature curve of a printed resistor indicated its potential as a temperature control switch. Furthermore, the measured reflection coefficient of a printed double-diamond antenna accords well with the simulated result. With unique merits such as no pollution, no requirement for encapsulation and easy recycling, the present printing approach is an important supplement to current printed electronics and has enormous practical value in the future. PMID:25484611

  12. Enzyme modification of starch with amylomaltase results in increasing gel melting point

    DEFF Research Database (Denmark)

    Hansen, Michael Riis; Blennow, Per Gunnar Andreas; Pedersen, Sven

    2009-01-01

    Melting properties of gelatin-based gels are fundamental for their functionality. With the aim at generating gelatin-like starch-based systems, thermodynamic properties of 20% (w/w) gels of 51 amylomaltase-(AM) (4-a-glucanotransferase; E.C. 2.4.1.25) modified starches, 7 non-enzyme-modified...... to 70 °C. Only for the combined AM and branching enzyme (BE) modified pea starches decreased Tp (from 79 to 61 °C) was obtained. This effect was followed by a decreased gel formation and hence a fully gelatin comparable gel was not obtained. A two-component principal component analysis (PCA) model...... starches and 2 gelatins were investigated using differential scanning calorimetry (DSC). AM modification generally increased gel peak temperature (Tp) and enthalpy of transition (¿H). The increase in Tp for the potato starches was from 65 to 74 °C, whereas for the maize starches it was elevated from 57...

  13. Liquidus projection of the Ag-Ba-Ge system and melting points of clathrate type-I compounds

    Energy Technology Data Exchange (ETDEWEB)

    Zeiringer, I.; Grytsiv, A. [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria); Broz, P. [Masaryk University, Faculty of Science, Department of Chemistry, Kotlarska 2, 61137 Brno (Czech Republic); Masaryk University, Central European Institute of Technology, CEITEC, Kamenice 753/5, 62500 Brno (Czech Republic); Rogl, P., E-mail: peter.franz.rogl@univie.ac.at [Institute of Physical Chemistry, University of Vienna, Waehringerstr. 42, 1090 Wien (Austria)

    2012-12-15

    The liquidus and solidus projection has been constructed for the Ag-Ba-Ge system up to 33.3 at% Ba, using electron micro probe analysis (EPMA), X-ray powder diffraction (XRD) and differential thermal analysis (DSC/DTA). Eight different primary crystallization regions were found: (Ge), Ba{sub 8}Ag{sub x}Ge{sub 46-x-y}{open_square}{sub y} ({kappa}{sub I}) ({open_square} is a vacancy), Ba{sub 6}Ag{sub x}Ge{sub 25-x} ({kappa}{sub Ix}), BaGe{sub 2}, Ba(Ag{sub 1-x}Ge{sub x}){sub 2} ({tau}{sub 1}), BaAg{sub 2-x}Ge{sub 2+x} ({tau}{sub 2}) BaAg{sub 5} and (Ag). The ternary invariant reactions have been determined for the region investigated and are the basis for a Schulz-Scheil diagram. The second part of this work provides a comprehensive compilation of melting points of ternary A{sub 8}T{sub x}M{sub 46-x} and quaternary (A=Sr, Ba, Eu; T=Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga; M=Si, Ge, Sn) clathrate type-I compounds and decomposition temperatures of inverse clathrate type-I Ge{sub 38}{l_brace}P,As,Sb{r_brace}{sub 8}{l_brace}Cl,Br,I{r_brace}{sub 8}, Si{sub 46-x}P{sub x}Te{sub y} and tin based compounds. - Graphical Abstract: Partial liquidus projection of the Ag-Ba-Ge system. Highlights: Black-Right-Pointing-Pointer The liquidus and solidus projection has been constructed for the Ag-Ba-Ge system up to 33.33 at% Ba. Black-Right-Pointing-Pointer Eight different primary crystallization fields have been found. Black-Right-Pointing-Pointer All the ternary compounds form congruently from the melt. Black-Right-Pointing-Pointer The ternary invariant reactions have been determined and are the basis for a Schulz-Scheil diagram.

  14. Allanite behaviour during incipient melting in the southern Central Alps

    DEFF Research Database (Denmark)

    Gregory, C.J.; Rubatto, D.; Hermann, J.

    2012-01-01

    86 43 84 24 120 91 181 302 260 Dy 134 219 311 363 147 353 80 499 350 712 1570 1190 Ho 16 30 40 48 16 46 9 64 45 89 231 158 Er 28 55 72 87 26 84 14 120 89 165 394 256 Tm 3 5 7 8 2 8 1 12 10 17 31 20 Yb 13 22 32 39 10 40 5 60 55 87 120 89 Lu 1.8 3 4 5 1.3 5 1 7 7 11 10 8 Hf 0.11 0.77 0.70 0.77 0.15 0...... 196 162 198 288 799 Ho 171 196 57 462 420 24 25 21 23 39 114 Er 351 403 120 1180 1030 45 47 40 43 81 232 Tm 36 41 14 152 131 4 4 4 5 9 26 Yb 175 209 87 920 805 24 23 20 33 58 147 Lu 20 25 12 112 99 3 3 3 4 7 17 Hf 0.80 0.75 0.25 0.32 0.24 0.22 0.48 0.43 0.10 0.24 0.18 Ta 0.02 0.34 0.04 0.05 0.05 0...

  15. Relationships between membrane water molecules and Patman equilibration kinetics at temperatures far above the phosphatidylcholine melting point.

    Science.gov (United States)

    Vaughn, Alexandra R; Bell, Thomas A; Gibbons, Elizabeth; Askew, Caitlin; Franchino, Hannabeth; Hirsche, Kelsey; Kemsley, Linea; Melchor, Stephanie; Moulton, Emma; Schwab, Morgan; Nelson, Jennifer; Bell, John D

    2015-04-01

    The naphthalene-based fluorescent probes Patman and Laurdan detect bilayer polarity at the level of the phospholipid glycerol backbone. This polarity increases with temperature in the liquid-crystalline phase of phosphatidylcholines and was observed even 90°C above the melting temperature. This study explores mechanisms associated with this phenomenon. Measurements of probe anisotropy and experiments conducted at 1M NaCl or KCl (to reduce water permittivity) revealed that this effect represents interactions of water molecules with the probes without proportional increases in probe mobility. Furthermore, comparison of emission spectra to Monte Carlo simulations indicated that the increased polarity represents elevation in probe access to water molecules rather than increased mobility of relevant bilayer waters. Equilibration of these probes with the membrane involves at least two steps which were distinguished by the membrane microenvironment reported by the probe. The difference in those microenvironments also changed with temperature in the liquid-crystalline phase in that the equilibrium state was less polar than the initial environment detected by Patman at temperatures near the melting point, more polar at higher temperatures, and again less polar as temperature was raised further. Laurdan also displayed this level of complexity during equilibration, although the relationship to temperature differed quantitatively from that experienced by Patman. This kinetic approach provides a novel way to study in molecular detail basic principles of what happens to the membrane environment around an individual amphipathic molecule as it penetrates the bilayer. Moreover, it provides evidence of unexpected and interesting membrane behaviors far from the phase transition. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Crack repair welding by CMT brazing using low melting point filler wire for long-term used steam turbine cases of Cr-Mo-V cast steels

    Energy Technology Data Exchange (ETDEWEB)

    Kadoi, Kota, E-mail: kadoi@hiroshima-u.ac.jp [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Murakami, Aoi; Shinozaki, Kenji; Yamamoto, Motomichi [Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima 739-8527 (Japan); Matsumura, Hideo [Chugoku Electric Power Co., 3-9-1 Kagamiyama, Higashi-Hiroshima 739-0046 (Japan)

    2016-06-01

    Surface melting by gas tungsten arc (GTA) welding and overlaying by cold metal transfer (CMT) brazing using low melting point filler wire were investigated to develop a repair process for cracks in worn cast steel of steam turbine cases. Cr-Mo-V cast steel, operated for 188,500 h at 566 °C, was used as the base material. Silver and gold brazing filler wires were used as overlaying materials to decrease the heat input into the base metal and the peak temperature during the welding thermal cycle. Microstructural analysis revealed that the worn cast steel test samples contained ferrite phases with intragranular precipitates of Cr{sub 7}C{sub 3}, Mo{sub 2}C, and CrSi{sub 2} and grain boundary precipitates of Cr{sub 23}C{sub 6} and Mo{sub 2}C. CMT brazing using low melting point filler wire was found to decrease the heat input and peak temperature during the thermal cycle of the process compared with those during GTA surface melting. Thus, the process helped to inhibit the formation of hardened phases such as intermetallics and martensite in the heat affected zone (HAZ). Additionally, in the case of CMT brazing using BAg-8, the change in the hardness of the HAZ was negligible even though other processes such as GTA surface melting cause significant changes. The creep-fatigue properties of weldments produced by CMT brazing with BAg-8 were the highest, and nearly the same as those of the base metal owing to the prevention of hardened phase formation. The number of fracture cycles using GTA surface melting and CMT brazing with BAu-4 was also quite small. Therefore, CMT brazing using low melting point filler wire such as BAg-8 is a promising candidate method for repairing steam turbine cases. However, it is necessary to take alloy segregation during turbine operation into account to design a suitable filler wire for practical use.

  17. Predicting critical temperatures of ionic and non-ionic fluids from thermophysical data obtained near the melting point

    Science.gov (United States)

    Weiss, Volker C.

    2015-10-01

    In the correlation and prediction of thermophysical data of fluids based on a corresponding-states approach, the critical temperature Tc plays a central role. For some fluids, in particular ionic ones, however, the critical region is difficult or even impossible to access experimentally. For molten salts, Tc is on the order of 3000 K, which makes accurate measurements a challenging task. Room temperature ionic liquids (RTILs) decompose thermally between 400 K and 600 K due to their organic constituents; this range of temperatures is hundreds of degrees below recent estimates of their Tc. In both cases, reliable methods to deduce Tc based on extrapolations of experimental data recorded at much lower temperatures near the triple or melting points are needed and useful because the critical point influences the fluid's behavior in the entire liquid region. Here, we propose to employ the scaling approach leading to universal fluid behavior [Román et al., J. Chem. Phys. 123, 124512 (2005)] to derive a very simple expression that allows one to estimate Tc from the density of the liquid, the surface tension, or the enthalpy of vaporization measured in a very narrow range of low temperatures. We demonstrate the validity of the approach for simple and polar neutral fluids, for which Tc is known, and then use the methodology to obtain estimates of Tc for ionic fluids. When comparing these estimates to those reported in the literature, good agreement is found for RTILs, whereas the ones for the molten salts NaCl and KCl are lower than previous estimates by 10%. The coexistence curve for ionic fluids is found to be more adequately described by an effective exponent of βeff = 0.5 than by βeff = 0.33.

  18. A practical approach to obtain the soil freezing characteristic curve and the freezing/melting point of a soil-water system

    NARCIS (Netherlands)

    Aukenthaler, Manuel; Brinkgreve, R.B.J.; Haxaire, A

    2016-01-01

    Knowing that extensive field tests and laboratory tests are time-consuming and expensive, this paper describes a practical approach to obtain crucial properties of frozen soil such as the soil freezing characteristic curve (SFCC), the freezing/melting point of a soil-water system and its hydraulic

  19. CATALYST-FREE REACTIONS UNDER SOLVENT-FEE CONDITIONS: MICROWAVE-ASSISTED SYNTHESIS OF HETEROCYCLIC HYDRAZONES BELOW THE MELTING POINT OF NEAT REACTANTS: JOURNAL ARTICLE

    Science.gov (United States)

    NRMRL-CIN-1437 Jeselnik, M., Varma*, R.S., Polanc, S., and Kocevar, M. Catalyst-free Reactions under Solvent-fee Conditions: Microwave-assisted Synthesis of Heterocyclic Hydrazones below the Melting Point of Neat Reactants. Published in: Chemical Communications 18:1716-1717 (200...

  20. Low melting point agarose beads as a standard method for plantlet regeneration from protoplasts within the Cichorium genus.

    Science.gov (United States)

    Deryckere, Dieter; Eeckhaut, Tom; Van Huylenbroeck, Johan; Van Bockstaele, Erik

    2012-12-01

    A standard method has been developed with which we are able to fully regenerate protoplasts of different Cichorium species. For the first time, endive protoplasts have been regenerated into plantlets. Protoplast regeneration is essential for somatic hybridizations. In this study, a standard method for plantlet regeneration from Cichorium protoplasts was developed. We evaluated the effect of the low melting point agarose (LMPA) bead technique on the regeneration capacity of protoplasts of seven C. intybus and four C. endivia genotypes. The LMPA bead technique was more efficient than culture in liquid or solid medium and allowed us to obtain plating efficiencies up to 4.9 % in C. intybus genotypes and efficiencies of up to 0.7 % in C. endivia genotypes. Moreover, the LMPA bead technique offers great advantages over liquid and solid culture systems: the media can be readily refreshed, protoplasts can be monitored separately, and microcalli can easily be removed from the beads. This increased efficiency was observed for all of the 11 Cichorium genotypes tested. Shoot formation was induced more efficiently when using 0.5 mg l(-1) indole-3-acetic acid-enriched medium (up to 87.5 % of the protoplast-derived calli started shoot development) compared to 1-naphthaleneacetic acid-enriched medium. The LMPA bead technique optimized in this study enabled for the first time the full plantlet regeneration from protoplasts of C. endivia genotypes and increased the protoplast regenerating ability in other Cichorium species. This fine-tuned LMPA bead technique can therefore be applied for protoplast regeneration after protoplast fusions of the genus Cichorium.

  1. Thermal property prediction and measurement of organic phase change materials in the liquid phase near the melting point

    International Nuclear Information System (INIS)

    O’Connor, William E.; Warzoha, Ronald; Weigand, Rebecca; Fleischer, Amy S.; Wemhoff, Aaron P.

    2014-01-01

    Highlights: • Liquid-phase thermal properties for five phase change materials were estimated. • Various liquid phase and phase transition thermal properties were measured. • The thermal diffusivity was found using a best path to prediction approach. • The thermal diffusivity predictive method shows 15% agreement for organic PCMs. - Abstract: Organic phase change materials (PCMs) are a popular choice for many thermal energy storage applications including solar energy, building envelope thermal barriers, and passive cooling of portable electronics. Since the extent of phase change during a heating or cooling process is dependent upon rapid thermal penetration into the PCM, accurate knowledge of the thermal diffusivity of the PCM in both solid and liquid phases is crucial. This study addresses the existing gaps in information for liquid-phase PCM properties by examining an approach that determines the best path to prediction (BPP) for the thermal diffusivity of both alkanes and unsaturated acids. Knowledge of the BPP will enable researchers to explore the influence of PCM molecular structure on bulk thermophysical properties, thereby allowing the fabrication of optimized PCMs. The BPP method determines which of the tens of thousands of combinations of 22 different available theoretical techniques provides best agreement with thermal diffusivity values based on reported or measured density, heat capacity, and thermal conductivity for each of five PCMs (heneicosane, tricosane, tetracosane, oleic acid, and linoleic acid) in the liquid phase near the melting point. Separate BPPs were calibrated for alkanes based on heneicosane and tetracosane, and for the unsaturated acids. The alkane and unsaturated acid BPPs were then tested on a variety of similar materials, showing agreement with reported/measured thermal diffusivity within ∼15% for all materials. The alkane BPP was then applied to find that increasing the length of alkane chains decreases the PCM thermal

  2. Incipient plasticity in metallic thin films

    NARCIS (Netherlands)

    Soer, W. A.; De Hosson, J. Th. M.; Minor, A. M.; Shan, Z.; Asif, S. A. Syed; Warren, O. L.

    2007-01-01

    The authors have compared the incipient plastic behaviors of Al and Al-Mg thin films during indentation under load control and displacement control. In Al-Mg, solute pinning limits the ability of dislocations to propagate into the crystal and thus substantially affects the appearance of plastic

  3. Incipient motion of gravel and coal beds

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    2Department of Civil Engineering, S R K R Engineering College, Bhimavaram. 534202, India e-mail: sdey@civil.iitkgp.ernet.in. MS received 15 January 2002. Abstract. An experimental study on incipient motion of gravel and coal beds under unidirectional steady-uniform flow is presented. Experiments were carried out in a ...

  4. The Ice-Vapor Interface and the Melting Point of Ice I-h for the Polarizable POL3 Water Model

    Czech Academy of Sciences Publication Activity Database

    Muchová, E.; Gladich, Ivan; Picaud, S.; Hoang, P. N. M.; Roeselová, Martina

    2011-01-01

    Roč. 115, č. 23 (2011), s. 5973-5982 ISSN 1089-5639 R&D Projects: GA ČR(CZ) GAP208/10/1724; GA MŠk LC512; GA MŠk MEB020919; GA MŠk MEB020715 Institutional research plan: CEZ:AV0Z40550506 Keywords : polarizable water force field * ice surface * melting point * ice slab Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.946, year: 2011

  5. The effect of coconut oil and palm oil as substituted oils to cocoa butter on chocolate bar texture and melting point

    Science.gov (United States)

    Limbardo, Rebecca Putri; Santoso, Herry; Witono, Judy Retti

    2017-05-01

    Cocoa butter has responsibility for dispersion medium to create a stable chocolate bar. Due to the economic reason, cocoa butter is partially or wholly substituted by edible oils e.g palm oil and coconut oil. The objective of the research was to observe the effect of oil substitution in the chocolate bar towards its melting point and texture. The research were divided in three steps which were preliminary research started with fat content analysis in cocoa powder, melting point analysis of substituted oils anc cocoa butter, and iodine number analysis in vegetable fats (cocoa butter, coconut oil, and palm oil), chocolate bar production with substitution 0%, 20%, 40%, 60%, 80%, and 100%wt of cocoa butter with each of substituted oils, and analysis process to determine the chocolate bar melting point with DSC and chocolate bar hardness with texture analyser. The increasement of substituted oils during substitution in chocolate bar would reduce the melting point of chocolate bar from 33.5°C to 31.6°C in palm oil substitution with cocoa butter and 33.5°C to 30.75°C in coconut oil substitution. The hardness of chocolate with palm oil were around 88.5 to 139 g on the 1st cycle and 22.75 to 132 g on the 2nd cycle. The hardness of chocolate with coconut oil were around 74.75 to 152.5 g on the 1st cycle and 53.25 to 132 g on the 2nd cycle. Maximum amount of fats substitution to produce a stable texture chocolate bar is 60% wt.

  6. The melting points of MgO up to 4 TPa predicted based on ab initio thermodynamic integration molecular dynamics.

    Science.gov (United States)

    Taniuchi, Takashi; Tsuchiya, Taku

    2018-03-21

    The melting curve of MgO is extended up to 4 TPa, corresponding to the Jovian core pressure, based on the one-step thermodynamic integration method implemented on ab initio molecular dynamics. The calculated melting temperatures are 3100 and 16 000 K at 0 and 500 GPa, respectively, which are consistent with previous experimental results, and 20 600 K at 3900 GPa, which is inconsistent with a recent experimental extrapolation, which implies the molten Jovian core. A quite small Clapeyron slope ([Formula: see text]) of [Formula: see text] is found at 3900 GPa due to comparable densities of the liquid and B2 phases under extreme compression. The Mg-O coordination number in the liquid phase is saturated at around 7.5 above 1 TPa and remains smaller than that in the B2 phase (8) even at 4 TPa, suggesting no density crossover between liquid and crystal and thus no further denser crystalline phases. Dynamical properties (atomic diffusivity and viscosity) are also investigated along the melting curve to understand these behaviors in greater detail.

  7. The melting points of MgO up to 4 TPa predicted based on ab initio thermodynamic integration molecular dynamics

    Science.gov (United States)

    Taniuchi, Takashi; Tsuchiya, Taku

    2018-03-01

    The melting curve of MgO is extended up to 4 TPa, corresponding to the Jovian core pressure, based on the one-step thermodynamic integration method implemented on ab initio molecular dynamics. The calculated melting temperatures are 3100 and 16 000 K at 0 and 500 GPa, respectively, which are consistent with previous experimental results, and 20 600 K at 3900 GPa, which is inconsistent with a recent experimental extrapolation, which implies the molten Jovian core. A quite small Clapeyron slope (dT/dP ) of 0.0+/- 0.5 is found at 3900 GPa due to comparable densities of the liquid and B2 phases under extreme compression. The Mg–O coordination number in the liquid phase is saturated at around 7.5 above 1 TPa and remains smaller than that in the B2 phase (8) even at 4 TPa, suggesting no density crossover between liquid and crystal and thus no further denser crystalline phases. Dynamical properties (atomic diffusivity and viscosity) are also investigated along the melting curve to understand these behaviors in greater detail.

  8. Effect of low-melting point phases on the microstructure and properties of spark plasma sintered and hot deformed Nd-Fe-B alloys

    Science.gov (United States)

    Zhang, Li; Wang, Meiyu; Yan, Xueliang; Lin, Ye; Shield, Jeffrey

    2018-04-01

    The effect of adding a low melting point Pr-Cu-Al alloy during spark plasma sintering of melt-spun Nd-Fe-B ribbons is investigated. Regions of coarse grains were reduced and overall grain refinement was observed after the addition of Pr68Cu25Al7, leading to an enhancement of coercivity from 12.7 kOe to 20.4 kOe. Hot deformation of the samples in the spark plasma sintering system resulted in the formation of platelet-like grains, producing crystallographic alignment and magnetic anisotropy. The hot deformation process improved the remanence and energy product but reduced the coercivity. The decrease of coercivity resulted from grain growth and aggregation of Pr and Nd elements at triple-junction phases.

  9. Ab initio analysis of a vacancy and a self-interstitial near single crystal silicon surfaces: Implications for intrinsic point defect incorporation during crystal growth from a melt

    Energy Technology Data Exchange (ETDEWEB)

    Kamiyama, Eiji; Sueoka, Koji [Department of Communication Engineering, Okayama Prefectural University, 111 Kuboki, Soja, Okayama 719-1197 (Japan); Vanhellemont, Jan [Department of Solid State Sciences, Ghent University, Krijgslaan 281-S1, Gent 9000 (Belgium)

    2012-10-15

    The microscopic model of the Si (001) crystal surface was investigated by first principles calculations to clarify the behavior of intrinsic point defects near crystal surfaces. A c(4 x 2) structure model was used to describe the crystal surface in contact with vacuum. The calculations show lower formation energy near the surface and the existence of formation energy differences between the surface and the bulk for both types of intrinsic point defects. The tetrahedral (T)-site and the dumbbell (DB)-site, in which a Si atom is captured from the surface and forms a self-interstitial, are found as stable sites near the third atomic layer. The T-site has a barrier of 0.48 eV, whereas the DB-site has no barrier for the interstitial to penetrate into the crystal from the vacuum. Si atoms in a melt can migrate and reach at the third layer during crystal growth when bulk diffusion coefficient is used. Therefore, the melt/solid interface is always a source of intrinsic point defects. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Using Paraffin with -10 deg C to 10 deg C Melting Point for Payload Thermal Energy Storage in SpaceX Dragon Trunk

    Science.gov (United States)

    Choi, Michael K.

    2013-01-01

    A concept of using paraffin wax phase change material (PCM) with a melting point between -10 deg C and 10 deg C for payload thermal energy storage in a Space Exploration Technologies (SpaceX) Dragon trunk is presented. It overcomes the problem of limited heater power available to a payload with significant radiators when the Dragon is berthed to the International Space Station (ISS). It stores adequate thermal energy to keep a payload warm without power for 6 hours during the transfer from the Dragon to an ExPRESS logistics carrier (ELC) on the ISS.

  11. Determination and microscopic study of incipient defects in irradiated power reactor fuel rods. Final report

    International Nuclear Information System (INIS)

    Pasupathi, V.; Perrin, J.S.; Roberts, E.

    1978-05-01

    This report presents the results of nondestructive and destructive examinations carried out on the Point Beach-1 (PWR) and Dresden-3 (BWR) candidate fuel rods selected for the study of pellet-clad interaction (PCI) induced incipient defects. In addition, the report includes results of examination of sections from Oskarshamn-1 (BWR) fuel rods. Eddy current examination of Point Beach-1 rods showed indications of possible incipient defects in the fuel rods. The profilometry and the gamma scan data also indicated that the source of the eddy current indications may be incipient defects. No failed rods or rods with incipient failure were found in the sample from Point Beach-1. Despite the lack of success in finding incipient defects and filed rods, the mechanism for fuel rod failures in Point Beach-1 is postulated to be PCI-related, with high startup rates and fuel handling being the key elements. Nine out of the 10 candidate fuel rods from Dresden-3 (BWR) were failed, and all the failed rods had leaked water so that the initial mechanism was observed. Examination of clad inner surfaces of the specimens from failed and unfailed rods showed fuel deposits of widely varying appearance. The deposits were found to contain uranium, cesium, and tellurium. Transmission electron microscopy of clad specimens showed evidence of microscopic strain. Metallographic examination of fuel pellets from the peak transient power location showed extensive grain boundary separation and axial movement of the fuel indicative of rapid release of fission products. Examination of Oskarshamn clad specimens did not show any stress corrosion crack (SCC) type defects. The defects found in the examinations appear to be related to secondary hydriding. The clad inner surface of the Oskarshamn specimens also showed uranium-rich deposits of varying features

  12. Processing and characterization of Al–Cu–Li alloy AA2195 undergoing scale up production through the vacuum induction melting technique

    International Nuclear Information System (INIS)

    Nayan, Niraj; Murty, S.V.S. Narayana; Jha, Abhay K.; Pant, Bhanu; Sharma, S.C.; George, Koshy M.; Sastry, G.V.S.

    2013-01-01

    The inherent properties of lithium, such as high reactivity and toxicity, relatively low density, low melting point, along with its high cost requires a special technological approach to cast Al–Cu–Li alloy AA2195 as compared to the conventional Direct Chill (DC) casting of aluminum alloys. This paper describes the processing requirements for melting and casting of 200 kg of Al–Cu–Li alloy in a Vacuum Induction Melting (VIM) furnace under dynamic inert atmosphere. The as-cast billets have been homogenized to remove microsegregation as well as to avoid incipient melting, and subsequently subjected for secondary metal processing operations viz., forging and rolling. The product in the form of 4 mm thick sheets was subjected to various heat treatments in T8 (Solution Treatment+WQ+CW+Aging) condition. Mechanical properties were evaluated at room temperature and were correlated with microstructures of the sheets processed under different conditions using transmission electron microscopy (TEM)

  13. Development of complex hydride-based all-solid-state lithium ion battery applying low melting point electrolyte

    Science.gov (United States)

    Suzuki, Shohei; Kawaji, Jun; Yoshida, Koji; Unemoto, Atsushi; Orimo, Shin-ichi

    2017-08-01

    A thermally durable all-solid-state lithium ion battery composed of a complex hydride, oxide electrolytes, and LiNi1/3Mn1/3Co1/3O2 active material is developed. This battery exhibits a discharge capacity of 56 mAh g-1, and the tenth capacity retention ratio is 29% at 150 °C owing to the large contact resistance between the electrolyte layer and the composite positive electrode layer. This large contact resistance is reduced by introducing an adhesive layer comprised of a mixture of LiBH4 and LiNH2 that is easily melted by thermal treatment and fills the voids and pores at the interface between the two layers. As a result, repeated charge-discharge cycles are successfully demonstrated at 150 °C with a high discharge capacity and discharge capacity retention ratio. The first discharge capacity is enhanced to 114 mAh g-1 and the capacity retention ratio at the tenth cycle is improved to 71%. These results demonstrate that using an adhesive layer is an effective measure to reduce the contact resistance and thereby enhance the performance of the battery.

  14. The link between Movability Number and Incipient Motion in river ...

    African Journals Online (AJOL)

    This allowed for a firmer definition of Incipient Motion as well as a new bedload transportation equation. Additional laboratory experimentation for Particle Reynolds number over the range 0.12-486 facilitated the improved prediction of Incipient Motion from a plot of the critical Movability Number vs. Particle Reynolds number ...

  15. The course of incipient diabetic nephropathy

    DEFF Research Database (Denmark)

    Christensen, Cramer; Mogensen, C E

    1985-01-01

    (incipient diabetic nephropathy) were studied. For comparison 18 normals, 23 diabetics with normal albumin excretion and 10 patients with overt nephropathy were also examined. Diastolic blood pressure (DBP) was elevated to 88 +/- 9 mmHg (mean +/- S.D.) compared to patients with normal urinary albumin...... excretion: 80 +/- 7 (S.D.) (2p = 0.13%) but was below pressures in patients with overt diabetic nephropathy 109 +/- 15 (2p = 0.002%). Glomerular filtration rate (GFR) was elevated to 142 +/- 21 ml/min (mean +/- S.D.) compared to 132 +/- 9 in patients with normal urinary albumin excretion (2p = 4.3%). Renal......With the aim of defining the transitional phase from normal or near normal albumin excretion to overt diabetic nephropathy, 23 male diabetics of more than 7 years' duration, below 40 years of age and a baseline urinary albumin excretion above 15 micrograms/min but without clinical proteinuria...

  16. Influence of Immersion Conditions on The Tensile Strength of Recycled Kevlar®/Polyester/Low-Melting-Point Polyester Nonwoven Geotextiles through Applying Statistical Analyses

    Directory of Open Access Journals (Sweden)

    Jing-Chzi Hsieh

    2016-05-01

    Full Text Available The recycled Kevlar®/polyester/low-melting-point polyester (recycled Kevlar®/PET/LPET nonwoven geotextiles are immersed in neutral, strong acid, and strong alkali solutions, respectively, at different temperatures for four months. Their tensile strength is then tested according to various immersion periods at various temperatures, in order to determine their durability to chemicals. For the purpose of analyzing the possible factors that influence mechanical properties of geotextiles under diverse environmental conditions, the experimental results and statistical analyses are incorporated in this study. Therefore, influences of the content of recycled Kevlar® fibers, implementation of thermal treatment, and immersion periods on the tensile strength of recycled Kevlar®/PET/LPET nonwoven geotextiles are examined, after which their influential levels are statistically determined by performing multiple regression analyses. According to the results, the tensile strength of nonwoven geotextiles can be enhanced by adding recycled Kevlar® fibers and thermal treatment.

  17. Incipient cytotoxicity: A time-independent measure of cytotoxic potency in vitro.

    Science.gov (United States)

    Gülden, Michael; Kähler, Daria; Seibert, Hasso

    2015-09-01

    Time is an important determinant of toxicity but largely ignored in in vitro toxicity assays where exposure times chosen are rather arbitrary. To investigate the impact of time on the cytotoxic potency of chemicals in vitro, the concentration dependent cytotoxic action of selected chemicals (surfactants, metals, oxidative stressors, a mitochondrial poison) was determined after various exposure times (1-72 h) in cultures of Balb/c 3T3 cells. Time affected the cytotoxic potency as well as the cytotoxic efficacy. The median cytotoxic concentrations, EC50, decreased and in most cases approached an "incipient" value, EC50,∞, within 72 h. Cytotoxicity due to mitochondrial insult occurred after a threshold time which was dependent on the medium glucose concentration. Within the chemicals studied the extent of potency change with time ranged from 3- to >1000-fold and the "time to incipient cytotoxicity", tic, from 4 to >72 h. Hence, also the relative cytotoxic potencies depend on exposure time. Ignoring this may lead to severe bias in toxicological hazard and risk assessment. Therefore it is recommended to determine the incipient cytotoxic potency of chemical compounds, represented by, e.g., the incipient median effect (EC50,∞), no effect (NEC∞) or lowest effect concentrations (LEC∞) instead of measures obtained after arbitrary exposure times. If this is not possible, the 72 h-potency measurements appear to be useful surrogates. These time-independent incipient potency values can be reasonably compared between substances, endpoints, cells and biological test systems and may serve to define points of departure for quantitative in vitro-in vivo extrapolations. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  18. Fat accumulation, fatty acids and melting point changes in broiler chick abdominal fat as affected by time of dietary fat feeding and slaughter age.

    Science.gov (United States)

    Carmona, J M; Lopez-Bote, C J; Daza, A; Rey, A I

    2017-03-23

    1. This work aims to quantify changes in fatty acid profile, melting point, abdominal fat accumulation and 2-thiobarbituric acid-reactive substances production depending on dietary fat source and age at slaughter, and to estimate the optimal date for the change from an unsaturated fat to a saturated fat diet or vice versa. 2. Treatments established were (1) birds fed 8% tallow from 21 to 49 d (TTT); (2) birds fed 8% tallow from 21 to 37 d and 8% sunflower oil from d 38 to 49 (TSS); (3) birds fed 8% sunflower oil from 21 to 37 d and 8% tallow from d 38 to 49 (STT); (4) birds fed 8% sunflower oil from 21 to 41 d and 8% tallow from d 42 to 49 (SST); (5) birds fed 8% sunflower oil from 21 to 49 d (SSS). Birds from each group were slaughtered on d 21, 29, 38, 40, 42, 44, 46 and 49. 3. The polyunsaturated fatty acids (PUFAs) proportion in the SSS group reached maximum values at d 40 and fitted a quadratic response. This group also showed a decrease in saturated fatty acids (SATs) and monounsaturated fatty acids (MUFAs) of lower intensity than the PUFA increase. The highest synthesis of SAT + MUFA was found in the SSS and TSS groups, whereas these had the lowest body-to-dietary PUFA ratio. 4. A high and quadratic increase in the MUFA proportion was observed during the first 10 d of feeding with the tallow-enriched diet at the expenses of the proportion of PUFA that quadratically decreased (minimum values at d 38). 5. Lipogenic and desaturation capacity decreased with age. 6. The TSS group increased tissue PUFA content faster that the SST group decreased PUFA content after the change in diet which indicates that the earlier feeding has to be taken into consideration for obtaining higher or lower changes in quality parameters. 7. The melting point of the SSS group showed a lower response to the dietary treatment in the initial period when compared to the TTT treatment. 8. The TTT, STT, SST and TSS groups showed similar fat accumulation, and changes in lipid

  19. Are Guidelines Needed for the Diagnosis and Management of Incipient Alzheimer's Disease and Mild Cognitive Impairment?

    Directory of Open Access Journals (Sweden)

    Katie Palmer

    2010-01-01

    Full Text Available Current research is aiming to push the boundaries of the point at which a diagnosis of Alzheimer Disease (AD can be made. Clinical syndromes such as Mild Cognitive Impairment (MCI and various clinical and biological markers of AD may help to identify people in the early stage of AD, before a full dementia syndrome is present. In the first part of this paper, we discuss whether MCI represents incipient AD, and examine some of the methods currently used in research to identify AD patients in the preclinical phase. In the second part, we discuss whether specific guidelines are needed for the diagnosis and management of MCI and incipient AD, and consider the potential impact of this on clinical practice and public health from the perspective of patients, caregivers, and healthcare providers.

  20. Structural phases arising from reconstructive and isostructural transitions in high-melting-point oxides under hydrostatic pressure: A first-principles study

    Science.gov (United States)

    Tian, Hao; Kuang, Xiao-Yu; Mao, Ai-Jie; Yang, Yurong; Xu, Changsong; Sayedaghaee, S. Omid; Bellaiche, L.

    2018-01-01

    High-melting-point oxides of chemical formula A B O3 with A =Ca , Sr, Ba and B =Zr , Hf are investigated as a function of hydrostatic pressure up to 200 GPa by combining first-principles calculations with a particle swarm optimization method. Ca- and Sr-based systems: (1) first undergo a reconstructive phase transition from a perovskite state to a novel structure that belongs to the post-post-perovskite family and (2) then experience an isostructural transition to a second, also new post-post-perovskite state at higher pressures, via the sudden formation of a specific out-of-plane B -O bond. In contrast, the studied Ba compounds evolve from a perovskite phase to a third novel post-post-perovskite structure via another reconstructive phase transition. The original characteristics of these three different post-post-perovskite states are emphasized. Unusual electronic properties, including significant piezochromic effects and an insulator-metal transition, are also reported and explained.

  1. Defining Incipient Subduction by Detecting Serpentenised Mantle in the Regional Magnetic Field

    Science.gov (United States)

    Pires, Rui; Clark, Stuart; Reis, Rui

    2017-04-01

    Keywords: Subduction initiation, Incipient Subduction, Active Margins, Southeast Asia, Mantle wedge The mechanisms of subduction initiation are poorly understood. One idea is to look for incipient subduction zones in the present day and see what features are common in these zones. However, incipient subduction zones are very difficult to detect and debate surrounds particular cases as to whether they qualify as incipient or not. In the analysis conducted in this work, we use the signal of the presence of a mantle wedge in the magnetic anomaly field as an indicator of incipient subduction. Each subduction zone exhibits variations in the particular responses of the system, such as slab-dip angle, maximum earthquake depths and volcanism to various parameters. So far, attempts to reduce the system to a dominate controlling parameter have failed, probably as a result of the limited number of cases and the large variety of controlling parameters. Parameters such as down-going and overriding plate morphology and velocity, mantle flow, the presence of plumes or not, sediment transport into the trench are a few of the parameters that have been studied in the literature. However, one of the characteristics associated with a subduction zones is the presence of a mantelic wedge as a result of the partial melt of the subducting plate and the development of a mantle wedge between the subducting plate and the overriding plate. The wedge is characterised by the presence of water (coming from sediments in the down-going plate) as well as lower temperatures (because the wedge is between two relatively cold lithospheres). As a results a serpentinized mantle wedge is formed that contains hydrous minerals, of which magnetite is an example, that alter the composition and properties of this region. According to Blakely et.al. (2005), this region exhibits both higher magnetic susceptibility and lower densities than the surrounding medium. We analysed five active margin boundaries located

  2. Current Signature Analysis as Diagnosis Media for Incipient Fault Detection

    Directory of Open Access Journals (Sweden)

    MIHET-POPA, L.

    2007-11-01

    Full Text Available This paper focuses on the experimental investigation for incipient fault detection and fault detection methods existing in the literature, using Wound Rotor Induction Machine (WRIM. Three main experiments (one for stator phase unbalance, one for rotor phase unbalance and one for turn-to-turn faults have been performed to study the electrical behavior of the WRIM. The article aims to provide further documentation for an advanced condition monitoring system, in order to avoid undesirable operating conditions and to detect and diagnose incipient electrical faults. A description of the measurement system and experimental investigation are presented and stator and rotor currents spectrum of the WRIM are analyzed.

  3. The link between Movability Number and Incipient Motion in river ...

    African Journals Online (AJOL)

    2009-06-05

    Jun 5, 2009 ... The concept of incipient motion has been of continuing interest to researchers and engineers working with sediment move- ...... pipe laws. J. Inst. Civ. Eng. 11 133-156. EINSTEIN HA (1942) Formulas for the transportation of bed load. Trans. ASCE 107 575-577. EINSTEIN HA (1950) The Bed Load Function ...

  4. Three feasible strategies to minimize kidney injury in 'incipient AKI'.

    Science.gov (United States)

    Perazella, Mark A; Coca, Steven G

    2013-08-01

    Acute kidney injury (AKI) is common and increasing in hospitalized patients. The earlier recognition of renal injury, at a stage described as 'incipient AKI', may allow renoprotective strategies to be initiated at a time when more kidney tissue is salvageable. 'Incipient AKI' represents renal injury as manifested by new-onset proteinuria, cellular activity on urine microscopy, or elevated novel biomarkers of kidney injury in the absence of clinical data that meet current diagnostic criteria for AKI. We propose three strategies to preserve kidney function and minimize further kidney injury in patients with 'incipient AKI'. These include--when appropriate for the prevailing cause of 'incipient AKI'--use of low-chloride-containing intravenous solutions, continued use of renin-angiotensin system antagonists, and use of diuretics to achieve adequate control of intravascular volume. The combined approach of the early diagnosis of AKI and early employment of feasible therapeutic strategies may slow the growth of clinical AKI, AKI requiring renal replacement therapy and chronic kidney disease, and might reduce AKI-associated mortality.

  5. Developing countries and incipient industrialization: a case study of ...

    African Journals Online (AJOL)

    Botswana's small and large towns offer good examples of incipient industrialization and enterprise clustering in a developing economy. Using data from Lobatse, a small industrial centre in Botswana, this brief paper shows that clustering in developing countries does not necessarily induce high inter-firm relationships as is ...

  6. Incipient sexual isolation in the nasuta-albomicans complex of ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Biosciences; Volume 26; Issue 3. Incipient sexual isolation in the nasuta-albomicans complex of Drosophila: mating preference in male-, female– and multiple-choice mating experiments. M T Tanuja N B Ramachandra H A Ranganath. Articles Volume 26 Issue 3 September 2001 pp 365-371 ...

  7. Thermodynamics of freezing and melting

    OpenAIRE

    Pedersen, Ulf Rørbæk; Costigliola, Lorenzo; Bailey, Nicholas; Schrøder, Thomas; Dyre, Jeppe C.

    2016-01-01

    Although the freezing of liquids and melting of crystals are fundamental for many areas of the sciences, even simple properties like the temperature?pressure relation along the melting line cannot be predicted today. Here we present a theory in which properties of the coexisting crystal and liquid phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variatio...

  8. Toy nanoindentation model and incipient plasticity

    Energy Technology Data Exchange (ETDEWEB)

    Plans, I. [G. Millan Institute for Fluid Dynamics, Nanoscience and Industrial Mathematics, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Laboratoire des Colloides, Verres et Nanomateriaux, UMR 5587, Universite Montpellier II and CNRS, 34095 Montpellier (France)], E-mail: plans@lcvn.univ-montp2.fr; Carpio, A. [Departamento de Matematica Aplicada, Universidad Complutense de Madrid, 28040 Madrid (Spain)], E-mail: carpio@mat.ucm.es; Bonilla, L.L. [G. Millan Institute for Fluid Dynamics, Nanoscience and Industrial Mathematics, Universidad Carlos III de Madrid, 28911 Leganes (Spain)], E-mail: bonilla@ing.uc3m.es

    2009-11-15

    A toy model of two dimensional nanoindentation in finite crystals is proposed. The crystal is described by periodized discrete elasticity whereas the indenter is a rigid strain field of triangular shape representing a hard knife-like indenter. Analysis of the model shows that there are a number of discontinuities in the load vs penetration depth plot which correspond to the creation of dislocation loops. The stress vs depth bifurcation diagram of the model reveals multistable stationary solutions that appear as the dislocation-free branch of solutions develops turning points for increasing stress. Dynamical simulations show that an increment of the applied load leads to nucleation of dislocation loops below the nanoindenter tip. Such dislocations travel inside the bulk of the crystal and accommodate at a certain depth in the sample. In agreement with experiments, hysteresis is observed if the stress is decreased after the first dislocation loop is created. Critical stress values for loop creation and their final location at equilibrium are calculated.

  9. Incipient Movement : designing the seamless and the scaleless

    DEFF Research Database (Denmark)

    Brabrand, Helle

    2012-01-01

    -space-presentations, confronting the actual time-space-depth of a viewer/player with virtual time-space-depth of transformation and deformation of drawing. Architectonic space limits and orients body movement. Conversely, architecture has the potential of setting free and expanding kinesthetic feeling-out in space. This twist......My project Incipient Movement relates seamless and scaleless parameters directly to the drawing of body-space. The project operates with a kind of topological sensing and taking form, by setting up series of relations between simple tectonic forces and forces of movement. The work twists body...... between oriented movement and movement in its incipiency is a basic dimension of architectural experience and related to dimensions in dance. Nevertheless these twists of movement-forces are rather neglected as architectonic design parameters....

  10. Software System for Finding the Incipient Faults in Power Transformers

    Directory of Open Access Journals (Sweden)

    Nikolina Petkova

    2015-05-01

    Full Text Available In this paper a new software system for finding of incipient faultsis presented.An experiment is made with real measurement of partial discharge(PD that appeared in power transformer. The software system usesacquisition data to define the real state of this transformer. One of the most important criteria for the power transformer’s state is the presence of partial discharges. The wave propagation caused by partial discharge depends on scheme of the winding and construction of the power equipment. In all cases, the PD source had a specific position so the wave measured from the PD –coupling device had a specific waveform. The waveform is different when PDcoupling device is put on a specific place. The waveform and the time of propagation are criteria for the localization of the source of incipient faults in the volume of power transformer.

  11. Solidification and Re-melting Phenomena During Slurry Preparation Using the RheoMetal™ Process

    Science.gov (United States)

    Payandeh, M.; Sabzevar, Mohsen Haddad; Jarfors, A. E. W.; Wessén, M.

    2017-12-01

    The melting sequence of the enthalpy exchange material (EEM) and formation of a slurry in the RheoMetal™ process was investigated. The EEM was extracted and quenched, together with a portion of the slurry at different processing times before complete melting. The EEM initially increased in size/diameter due to melt freezing onto its surface, forming a freeze- on layer. The initial growth of this layer was followed by a period of a constant diameter of the EEM with subsequent melting and decrease of diameter. Microstructural characterization of the size and morphology of different phases in the EEM and in the freeze-on layer was made. Dendritic equiaxed grains and eutectic regions containing Si particles and Cu-bearing particles and Fe-rich particles were observed in the as-cast EEM. The freeze-on layer consisted of dendritic aluminum tilted by about 30 deg in the upstream direction, caused by the rotation of the EEM. Energy dispersion spectroscopy analysis showed that the freeze-on layer had a composition corresponding to an alloy with higher melting point than the EEM and thus shielding the EEM from the surrounding melt. Microstructural changes in the EEM showed that temperature rapidly increased to 768 K (495 °C), indicated by incipient melting of the lowest temperature melting eutectic in triple junction grain boundary regions with Al2Cu and Al5Mg8Si6Cu2 phases present. As the EEM temperature increased further the binary Al-Si eutectic started to melt to form a region of a fully developed coherent mushy state. Experimental results and a thermal model indicated that as the dendrites spheroidized near to the interface at the EEM/freeze-on layer reached a mushy state with 25 pct solid fraction, coherency was lost and disintegration of the freeze-on layer took place. Subsequently, in the absence of the shielding effect from the freeze-on Layer, the EEM continued to disintegrate with a coherency limit of a solid fraction estimated to be 50 pct.

  12. Evaluation of diagnostic ability of CCD digital radiography in the detection of incipient dental caries

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Wan; Lee, Byung Do [Wonkwang University College of Medicine, Iksan (Korea, Republic of)

    2003-03-15

    The purpose of this experiment was to evaluate the diagnostic ability of a CCD-based digital system (CDX-2000HQ) in the detection of incipient dental caries. 93 extracted human teeth with sound proximal surfaces and interproximal artificial cavities were radiographed using 4 imaging methods. Automatically processed No.2 Insight film (Eastman Kodak Co., U.S.A.) was used for conventional radiography, scanned images of conventional radiograms for indirect digital radiography were used. For the direct digital radiography, the CDX-2000HQ CCD system (Biomedisys Co. Korea) was used. The subtraction images were made from two direct digital images by Sunny program in the CDX-2000HQ system. Two radiologists and three endodontists examined the presence of lesions using a five-point confidence scale and compared the diagnostic ability by ROC (Receiver Operating Characteristic) analysis and one way ANOVA test. The mean ROC areas of conventional radiography, indirect digital radiography, direct digital radiography, and digital subtraction radiography were 0.9093, 0.9102, 0.9184, and 0.9056, respectively. The diagnostic ability of direct digital radiography was better than the other imaging modalities, but there were no statistical differences among these imaging modalities (p>0.05). These results indicate that new CCD-based digital systems (CDX-2000HQ) have the potential to serve as an alternative to conventional radiography in the detection of incipient dental caries.

  13. Evaluation of diagnostic ability of CCD digital radiography in the detection of incipient dental caries

    International Nuclear Information System (INIS)

    Lee, Wan; Lee, Byung Do

    2003-01-01

    The purpose of this experiment was to evaluate the diagnostic ability of a CCD-based digital system (CDX-2000HQ) in the detection of incipient dental caries. 93 extracted human teeth with sound proximal surfaces and interproximal artificial cavities were radiographed using 4 imaging methods. Automatically processed No.2 Insight film (Eastman Kodak Co., U.S.A.) was used for conventional radiography, scanned images of conventional radiograms for indirect digital radiography were used. For the direct digital radiography, the CDX-2000HQ CCD system (Biomedisys Co. Korea) was used. The subtraction images were made from two direct digital images by Sunny program in the CDX-2000HQ system. Two radiologists and three endodontists examined the presence of lesions using a five-point confidence scale and compared the diagnostic ability by ROC (Receiver Operating Characteristic) analysis and one way ANOVA test. The mean ROC areas of conventional radiography, indirect digital radiography, direct digital radiography, and digital subtraction radiography were 0.9093, 0.9102, 0.9184, and 0.9056, respectively. The diagnostic ability of direct digital radiography was better than the other imaging modalities, but there were no statistical differences among these imaging modalities (p>0.05). These results indicate that new CCD-based digital systems (CDX-2000HQ) have the potential to serve as an alternative to conventional radiography in the detection of incipient dental caries.

  14. Filament stretching rheometry of polymer melts

    DEFF Research Database (Denmark)

    Hassager, Ole; Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz

    2005-01-01

    The Filament Stretching Rheometry (FSR) method developed by Sridhar, McKinley and coworkers for polymer solutions has been extended to be used also for polymer melts. The design of a melt-FSR will be described and differences to conventional melt elongational rheometers will be pointed out. Results...

  15. Design of Low-Melting Point Compositions Suitable for Transient Liquid Phase Sintering of PM Steels Based on a Thermodynamic and Kinetic Study

    Science.gov (United States)

    Bernardo, Elena; de Oro, Raquel; Campos, Mónica; Torralba, José Manuel

    2014-04-01

    The possibility of tailoring the characteristics of a liquid metal is an important asset in a wide number of processing techniques. For most of these processes, the nature and degree of the interaction between liquid and solid phases are usually a focus of interest since they determine liquid properties such as wettability and infiltration capacity. Particularly, within the powder metallurgy (PM) technology, it is considered one of the key aspects to obtain high performance steels through liquid phase sintering. In this work, it is proved how thermodynamic and kinetics software is a powerful tool to study the liquid/solid interactions. The assessment of different liquid phase promoters for transient liquid phase sintering is addressed through the use of ThermoCalc and DICTRA calculations. Besides melting temperatures, particular attention is given to the solubility phenomena between the phases and the kinetics of these processes. Experimental validation of thermodynamic results is carried out by wetting and infiltration experiments at high temperatures. Compositions presenting different liquid/solid solubility are evaluated and directly correlated to the behavior of the liquid during a real sintering process. Therefore, this work opens the possibility to optimize liquid phase compositions and predict the liquid behavior from the design step, which is considered of high technological value for the PM industry.

  16. Incipient fault detection and power system protection for spaceborne systems

    Science.gov (United States)

    Russell, B. Don; Hackler, Irene M.

    1987-01-01

    A program was initiated to study the feasibility of using advanced terrestrial power system protection techniques for spacecraft power systems. It was designed to enhance and automate spacecraft power distribution systems in the areas of safety, reliability and maintenance. The proposed power management/distribution system is described as well as security assessment and control, incipient and low current fault detection, and the proposed spaceborne protection system. It is noted that the intelligent remote power controller permits the implementation of digital relaying algorithms with both adaptive and programmable characteristics.

  17. Incipient cognition solves the spatial reciprocity conundrum of cooperation.

    Directory of Open Access Journals (Sweden)

    Jeromos Vukov

    Full Text Available BACKGROUND: From the simplest living organisms to human societies, cooperation among individuals emerges as a paradox difficult to explain and describe mathematically, although very often observed in reality. Evolutionary game theory offers an excellent toolbar to investigate this issue. Spatial structure has been one of the first mechanisms promoting cooperation; however, alone it only opens a narrow window of viability. METHODOLOGY/PRINCIPAL FINDINGS: Here we equip individuals with incipient cognitive abilities, and investigate the evolution of cooperation in a spatial world where retaliation, forgiveness, treason and mutualism may coexist, as individuals engage in Prisoner's Dilemma games. In the model, individuals are able to distinguish their partners and act towards them based on previous interactions. We show how the simplest level of cognition, alone, can lead to the emergence of cooperation. CONCLUSIONS/SIGNIFICANCE: Despite the incipient nature of the individuals' cognitive abilities, cooperation emerges for unprecedented values of the temptation to cheat, being also robust to invasion by cheaters, errors in decision making and inaccuracy of imitation, features akin to many species, including humans.

  18. Controlling incipient oxidation of pyrite for improved rejection. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, R.H.; Richardson, P.E.; Tao, D.P.

    1996-04-01

    It is well known that superficial oxidation of pyrite produces a hydrophobic sulfur-rich surface and creates problems in separating the mineral from coal using surface-based processes such as flotation and agglomeration. Numerous studies of pyrite oxidation have been conducted but most of them were concerned with the advanced stages of oxidation, and as a result it was not possible to establish a relationship between oxidation and flotation behavior. A better understanding of the mechanisms and kinetics of the incipient oxidation reactions, which may vary with the origin, morphology, texture, and solid state properties of pyrite, can lead to the development of new processes that can improve pyrite rejection from coal. This project is aimed at better understanding of the mechanisms involved during the initial stages of pyrite oxidation to foster the development of advanced coal cleaning technologies. Studies were conducted by fracturing pyrite electrodes in-situ in an electrochemical cell to create virgin surfaces. Electrochemical and photoelectrochemical techniques were employed to characterize the incipient oxidation of pyrite in aqueous solutions. Microflotation tests were conducted to obtain information on the hydrophobicity of pyrite under controlled E{sub h} and pH conditions, and the results were correlated with electrochemical studies.

  19. Coercivity enhancement of NdFeB sintered magnets by low melting point Dy{sub 32.5}Fe{sub 62}Cu{sub 5.5} alloy modification

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Liping; Ma, Tianyu, E-mail: maty@zju.edu.cn; Zhang, Pei; Jin, Jiaying; Yan, Mi, E-mail: mse_yanmi@zju.edu.cn

    2014-04-15

    To improve coercivity without sacrificing other magnetic performance of NdFeB sintered magnets, a low melting point Dy{sub 32.5}Fe{sub 62}Cu{sub 5.5} alloy was introduced as an intergranular additive. Magnetic properties and microstructure of the magnets with different Dy{sub 32.5}Fe{sub 62}Cu{sub 5.5} contents were studied. At the optimum addition of 3 wt%, coercivity H{sub cj} was enhanced from 12.7 to 15.2 kOe, the maximum magnetic energy product (BH){sub max} was simultaneously increased from 46.6 to 47.8 MG Oe, accompanied by a slight reduction in remanence B{sub r}. Further investigation on microstructure and grain boundary composition indicated that the enhanced H{sub cj} and (BH){sub max} could be attributed to the refined and uniform 2:14:1 phase grains, continuous grain boundaries and a (Nd,Dy){sub 2}Fe{sub 14}B hardening shell surrounding the 2:14:1 phase grains. - Highlights: • Low melting-point Dy{sub 32.5}Fe{sub 62}Cu{sub 5.5} alloy was introduced to NdFeB magnets. • The doped magnet exhibits enhanced coercivity and maximum energy product. • (Nd,Dy){sub 2}Fe{sub 14}B shell was expected to form in the surface of Nd{sub 2}Fe{sub 14}B grains. • The continuous grain boundary layer formed between neighboring Nd{sub 2}Fe{sub 14}B grains.

  20. A measurement-based technique for incipient anomaly detection

    KAUST Repository

    Harrou, Fouzi

    2016-06-13

    Fault detection is essential for safe operation of various engineering systems. Principal component analysis (PCA) has been widely used in monitoring highly correlated process variables. Conventional PCA-based methods, nevertheless, often fail to detect small or incipient faults. In this paper, we develop new PCA-based monitoring charts, combining PCA with multivariate memory control charts, such as the multivariate cumulative sum (MCUSUM) and multivariate exponentially weighted moving average (MEWMA) monitoring schemes. The multivariate control charts with memory are sensitive to small and moderate faults in the process mean, which significantly improves the performance of PCA methods and widen their applicability in practice. Using simulated data, we demonstrate that the proposed PCA-based MEWMA and MCUSUM control charts are more effective in detecting small shifts in the mean of the multivariate process variables, and outperform the conventional PCA-based monitoring charts. © 2015 IEEE.

  1. Petrological Geodynamics of Mantle Melting I. AlphaMELTS + Multiphase Flow: Dynamic Equilibrium Melting, Method and Results

    Directory of Open Access Journals (Sweden)

    Massimiliano Tirone

    2017-10-01

    with time, the melt and solid composition approach the composition that is found from a dynamic batch melting model which assumes the velocities of melt and residual solid to be the same. Time dependent melt fluctuations can be observed under certain conditions. In this case the composition of the melt that reaches the top side of the model (exit point may vary to some extent. A consistent result of the model under various conditions is that the volume of the first melt that arrives at the exit point is substantially larger than any later melt output. The analogy with large magma emplacements associated to continental break-up or formation of oceanic plateaus seems to suggest that these events are the direct consequence of a dynamic two-phase flow process. Even though chemical equilibrium between melt and the residual solid is imposed locally in space, bulk composition of the whole system (solid+melt varies with depth and may also vary with time, mainly as the result of the changes of the melt abundance. Potential factors that can influence the melting process such as bulk composition, temperature and mantle upwelling velocity at the top boundary (passive flow or bottom boundary (active flow should be addressed more systematically before the DEM model in this study and the dynamic fractional melting (DFM model that will be introduced in the second installment can be applied to interpret real petrological data. Complete data files of most of the simulations and four animations are available following the data repository link provided in the Supplementary Material.

  2. Multiscale Models of Melting Arctic Sea Ice

    Science.gov (United States)

    2014-09-30

    Sea ice reflectance or albedo , a key parameter in climate modeling, is primarily determined by melt pond and ice floe configurations. Ice - albedo ...determine their albedo - a key parameter in climate modeling. Here we explore the possibility of a conceptual sea ice climate model passing through a...bifurcation points. Ising model for melt ponds on Arctic sea ice Y. Ma, I. Sudakov, and K. M. Golden Abstract: The albedo of melting

  3. Brazilian and Mexican experiences in the study of incipient domestication.

    Science.gov (United States)

    Lins Neto, Ernani Machado de Freitas; Peroni, Nivaldo; Casas, Alejandro; Parra, Fabiola; Aguirre, Xitlali; Guillén, Susana; Albuquerque, Ulysses Paulino

    2014-04-02

    diverse cultural and ecological contexts for a better understanding of evolution under incipient processes of domestication. Higher research effort is particularly required in Brazil, where studies on this topic are scarcer than in Mexico but where diversity of human cultures managing their also high plant resources diversity offer high potential for documenting the diversity of mechanisms of artificial selection and evolutionary trends. Comparisons and evaluations of incipient domestication in the regions studied as well as the Andean area would significantly contribute to understanding origins and diffusion of the experience of managing and domesticating plants.

  4. Genomics of Rapid Incipient Speciation in Sympatric Threespine Stickleback.

    Directory of Open Access Journals (Sweden)

    David A Marques

    2016-02-01

    Full Text Available Ecological speciation is the process by which reproductively isolated populations emerge as a consequence of divergent natural or ecologically-mediated sexual selection. Most genomic studies of ecological speciation have investigated allopatric populations, making it difficult to infer reproductive isolation. The few studies on sympatric ecotypes have focused on advanced stages of the speciation process after thousands of generations of divergence. As a consequence, we still do not know what genomic signatures of the early onset of ecological speciation look like. Here, we examined genomic differentiation among migratory lake and resident stream ecotypes of threespine stickleback reproducing in sympatry in one stream, and in parapatry in another stream. Importantly, these ecotypes started diverging less than 150 years ago. We obtained 34,756 SNPs with restriction-site associated DNA sequencing and identified genomic islands of differentiation using a Hidden Markov Model approach. Consistent with incipient ecological speciation, we found significant genomic differentiation between ecotypes both in sympatry and parapatry. Of 19 islands of differentiation resisting gene flow in sympatry, all were also differentiated in parapatry and were thus likely driven by divergent selection among habitats. These islands clustered in quantitative trait loci controlling divergent traits among the ecotypes, many of them concentrated in one region with low to intermediate recombination. Our findings suggest that adaptive genomic differentiation at many genetic loci can arise and persist in sympatry at the very early stage of ecotype divergence, and that the genomic architecture of adaptation may facilitate this.

  5. Thermodynamics of freezing and melting

    DEFF Research Database (Denmark)

    Pedersen, Ulf Rørbæk; Costigliola, Lorenzo; Bailey, Nicholas

    2016-01-01

    phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variation along this line of the reduced crystalline vibrational mean-square displacement (the Lindemann ratio...

  6. Molecular dynamics simulations on the melting of gold nanoparticles

    Science.gov (United States)

    Qiao, Zhiwei; Feng, Haijun; Zhou, Jian

    2014-01-01

    Molecular dynamics is employed to study the melting of bulk gold and gold nanoparticles. PCFF, Sutton-Chen and COMPASS force fields are adopted to study the melting point of bulk gold and we find out that the Sutton-Chen force field is the most accurate model in predicting the melting point of bulk gold. Consequently, the Sutton-Chen force field is applied to study the melting points of spherical gold nanoparticles with different diameters. Variations of diffusion coefficient, potential energy and translational order parameter with temperature are analyzed. The simulated melting points of gold nanoparticles are between 615∼1115 K, which are much lower than that of bulk gold (1336 K). As the diameter of gold nanoparticle drops, the melting point also descends. The melting mechanism is also analyzed for gold nanoparticles.

  7. Robust Fault Diagnosis Design for Linear Multiagent Systems with Incipient Faults

    Directory of Open Access Journals (Sweden)

    Jingping Xia

    2015-01-01

    Full Text Available The design of a robust fault estimation observer is studied for linear multiagent systems subject to incipient faults. By considering the fact that incipient faults are in low-frequency domain, the fault estimation of such faults is proposed for discrete-time multiagent systems based on finite-frequency technique. Moreover, using the decomposition design, an equivalent conclusion is given. Simulation results of a numerical example are presented to demonstrate the effectiveness of the proposed techniques.

  8. Evidence of Incipient Forest Transition in Southern Mexico

    Science.gov (United States)

    Vaca, Raúl Abel; Golicher, Duncan John; Cayuela, Luis; Hewson, Jenny; Steininger, Marc

    2012-01-01

    Case studies of land use change have suggested that deforestation across Southern Mexico is accelerating. However, forest transition theory predicts that trajectories of change can be modified by economic factors, leading to spatial and temporal heterogeneity in rates of change that may take the form of the Environmental Kuznets Curve (EKC). This study aimed to assess the evidence regarding potential forest transition in Southern Mexico by classifying regional forest cover change using Landsat imagery from 1990 through to 2006. Patterns of forest cover change were found to be complex and non-linear. When rates of forest loss were averaged over 342 municipalities using mixed-effects modelling the results showed a significant (p<0.001) overall reduction of the mean rate of forest loss from 0.85% per year in the 1990–2000 period to 0.67% in the 2000–2006 period. The overall regional annual rate of deforestation has fallen from 0.33% to 0.28% from the 1990s to 2000s. A high proportion of the spatial variability in forest cover change cannot be explained statistically. However analysis using spline based general additive models detected underlying relationships between forest cover and income or population density of a form consistent with the EKC. The incipient forest transition has not, as yet, resulted in widespread reforestation. Forest recovery remains below 0.20% per year. Reforestation is mostly the result of passive processes associated with reductions in the intensity of land use. Deforestation continues to occur at high rates in some focal areas. A transition could be accelerated if there were a broader recognition among policy makers that the regional rate of forest loss has now begun to fall. The changing trajectory provides an opportunity to actively restore forest cover through stimulating afforestation and stimulating more sustainable land use practices. The results have clear implications for policy aimed at carbon sequestration through reducing

  9. Evidence of incipient forest transition in Southern Mexico.

    Directory of Open Access Journals (Sweden)

    Raúl Abel Vaca

    Full Text Available Case studies of land use change have suggested that deforestation across Southern Mexico is accelerating. However, forest transition theory predicts that trajectories of change can be modified by economic factors, leading to spatial and temporal heterogeneity in rates of change that may take the form of the Environmental Kuznets Curve (EKC. This study aimed to assess the evidence regarding potential forest transition in Southern Mexico by classifying regional forest cover change using Landsat imagery from 1990 through to 2006. Patterns of forest cover change were found to be complex and non-linear. When rates of forest loss were averaged over 342 municipalities using mixed-effects modelling the results showed a significant (p<0.001 overall reduction of the mean rate of forest loss from 0.85% per year in the 1990-2000 period to 0.67% in the 2000-2006 period. The overall regional annual rate of deforestation has fallen from 0.33% to 0.28% from the 1990s to 2000s. A high proportion of the spatial variability in forest cover change cannot be explained statistically. However analysis using spline based general additive models detected underlying relationships between forest cover and income or population density of a form consistent with the EKC. The incipient forest transition has not, as yet, resulted in widespread reforestation. Forest recovery remains below 0.20% per year. Reforestation is mostly the result of passive processes associated with reductions in the intensity of land use. Deforestation continues to occur at high rates in some focal areas. A transition could be accelerated if there were a broader recognition among policy makers that the regional rate of forest loss has now begun to fall. The changing trajectory provides an opportunity to actively restore forest cover through stimulating afforestation and stimulating more sustainable land use practices. The results have clear implications for policy aimed at carbon sequestration through

  10. Lipídios estruturados obtidos a partir da mistura de gordura de frango, sua estearina e triacilgliceróis de cadeia média: II- pontos de amolecimento e fusão Structured lipids from chicken fat, its stearin, and medium chain triacyglycerol blends: II- softening and melting points

    Directory of Open Access Journals (Sweden)

    Ming Chih Chiu

    2008-01-01

    Full Text Available The aim of the present work is to investigate the effects of blending and chemical interesterification reactions on the softening and melting behavior of chicken fat, its stearin and medium chain triacylglycerols, and blends thereof in various ratios. Chemical interesterification is a promising alternative to the current processes of modifying the physical properties of fats. In the experimental design 7 samples corresponding to 7 different blend proportions were used. The results were represented in triangular diagrams. The addition of stearin influenced the softening and melting points. The mixture response surface methodology proved to be an extremely useful tool for the optimization of the fat mixtures.

  11. Melting under shock compression

    International Nuclear Information System (INIS)

    Bennett, B.I.

    1980-10-01

    A simple model, using experimentally measured shock and particle velocities, is applied to the Lindemann melting formula to predict the density, temperature, and pressure at which a material will melt when shocked from room temperature and zero pressure initial conditions

  12. [Solder melting torches].

    Science.gov (United States)

    Cubero Postigo, G

    1988-11-01

    In this study about melting and torchs employed in solder in fixed prosthodontics, it's analysed the accurate melting, adequate quantity, as well as protection of adjacent tissues with an accurate anti-melting. The torch chosen is the oxyacetylene burner, because its greater calorific power.

  13. Quasi-equilibrium melting of quartzite upon extreme friction

    Science.gov (United States)

    Lee, Sung Keun; Han, Raehee; Kim, Eun Jeong; Jeong, Gi Young; Khim, Hoon; Hirose, Takehiro

    2017-06-01

    The friction on fault planes that controls how rocks slide during earthquakes decreases significantly as a result of complex fault-lubrication processes involving frictional melting. Fault friction has been characterized in terms of the preferential melting of minerals with low melting points--so-called disequilibrium melting. Quartz, which has a high melting temperature of about 1,726 °C and is a major component of crustal rocks, is not expected to melt often during seismic slip. Here we use high-velocity friction experiments on quartzite to show that quartz can melt at temperatures of 1,350 to 1,500 °C. This implies that quartz within a fault plane undergoing rapid friction sliding could melt at substantially lower temperatures than expected. We suggest that depression of the melting temperature is caused by the preferential melting of ultra-fine particles and metastable melting of β-quartz at about 1,400 °C during extreme frictional slip. The results for quartzite are applicable to complex rocks because of the observed prevalence of dynamic grain fragmentation, the preferential melting of smaller grains and the kinetic preference of β-quartz formation during frictional sliding. We postulate that frictional melting of quartz on a fault plane at temperatures substantially below the melting temperature could facilitate slip-weakening and lead to large earthquakes.

  14. Localization of incipient tip vortex cavitation using ray based matched field inversion method

    Science.gov (United States)

    Kim, Dongho; Seong, Woojae; Choo, Youngmin; Lee, Jeunghoon

    2015-10-01

    Cavitation of marine propeller is one of the main contributing factors of broadband radiated ship noise. In this research, an algorithm for the source localization of incipient vortex cavitation is suggested. Incipient cavitation is modeled as monopole type source and matched-field inversion method is applied to find the source position by comparing the spatial correlation between measured and replicated pressure fields at the receiver array. The accuracy of source localization is improved by broadband matched-field inversion technique that enhances correlation by incoherently averaging correlations of individual frequencies. Suggested localization algorithm is verified through known virtual source and model test conducted in Samsung ship model basin cavitation tunnel. It is found that suggested localization algorithm enables efficient localization of incipient tip vortex cavitation using a few pressure data measured on the outer hull above the propeller and practically applicable to the typically performed model scale experiment in a cavitation tunnel at the early design stage.

  15. Fault prediction for nonlinear stochastic system with incipient faults based on particle filter and nonlinear regression.

    Science.gov (United States)

    Ding, Bo; Fang, Huajing

    2017-05-01

    This paper is concerned with the fault prediction for the nonlinear stochastic system with incipient faults. Based on the particle filter and the reasonable assumption about the incipient faults, the modified fault estimation algorithm is proposed, and the system state is estimated simultaneously. According to the modified fault estimation, an intuitive fault detection strategy is introduced. Once each of the incipient fault is detected, the parameters of which are identified by a nonlinear regression method. Then, based on the estimated parameters, the future fault signal can be predicted. Finally, the effectiveness of the proposed method is verified by the simulations of the Three-tank system. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  16. Investigation of Melting Dynamics of Hafnium Clusters.

    Science.gov (United States)

    Ng, Wei Chun; Lim, Thong Leng; Yoon, Tiem Leong

    2017-03-27

    Melting dynamics of hafnium clusters are investigated using a novel approach based on the idea of the chemical similarity index. Ground state configurations of small hafnium clusters are first derived using Basin-Hopping and Genetic Algorithm in the parallel tempering mode, employing the COMB potential in the energy calculator. These assumed ground state structures are verified by using the Low Lying Structures (LLS) method. The melting process is carried out either by using the direct heating method or prolonged simulated annealing. The melting point is identified by a caloric curve. However, it is found that the global similarity index is much more superior in locating premelting and total melting points of hafnium clusters.

  17. Toward a coherent model for the melting behavior of the deep Earth's mantle

    Science.gov (United States)

    Andrault, D.; Bolfan-Casanova, N.; Bouhifd, M. A.; Boujibar, A.; Garbarino, G.; Manthilake, G.; Mezouar, M.; Monteux, J.; Parisiades, P.; Pesce, G.

    2017-04-01

    Knowledge of melting properties is critical to predict the nature and the fate of melts produced in the deep mantle. Early in the Earth's history, melting properties controlled the magma ocean crystallization, which potentially induced chemical segregation in distinct reservoirs. Today, partial melting most probably occurs in the lowermost mantle as well as at mid upper-mantle depths, which control important aspects of mantle dynamics, including some types of volcanism. Unfortunately, despite major experimental and theoretical efforts, major controversies remain about several aspects of mantle melting. For example, the liquidus of the mantle was reported (for peridotitic or chondritic-type composition) with a temperature difference of ∼1000 K at high mantle depths. Also, the Fe partitioning coefficient (DFeBg/melt) between bridgmanite (Bg, the major lower mantle mineral) and a melt was reported between ∼0.1 and ∼0.5, for a mantle depth of ∼2000 km. Until now, these uncertainties had prevented the construction of a coherent picture of the melting behavior of the deep mantle. In this article, we perform a critical review of previous works and develop a coherent, semi-quantitative, model. We first address the melting curve of Bg with the help of original experimental measurements, which yields a constraint on the volume change upon melting (ΔVm). Secondly, we apply a basic thermodynamical approach to discuss the melting behavior of mineralogical assemblages made of fractions of Bg, CaSiO3-perovskite and (Mg,Fe)O-ferropericlase. Our analysis yields quantitative constraints on the SiO2-content in the pseudo-eutectic melt and the degree of partial melting (F) as a function of pressure, temperature and mantle composition; For examples, we find that F could be more than 40% at the solidus temperature, except if the presence of volatile elements induces incipient melting. We then discuss the melt buoyancy in a partial molten lower mantle as a function of pressure

  18. Incipient Stator Insulation Fault Detection of Permanent Magnet Synchronous Wind Generators Based on Hilbert–Huang Transformation

    DEFF Research Database (Denmark)

    Wang, Chao; Liu, Xiao; Chen, Zhe

    2014-01-01

    Incipient stator winding fault in permanent magnet synchronous wind generators (PMSWGs) is very difficult to be detected as the fault generated variations in terminal electrical parameters are very weak and chaotic. This paper simulates the incipient stator winding faults at different degree...

  19. Correlation between laser fluorescence readings and volume of tooth preparation in incipient occlusal caries in vitro.

    Science.gov (United States)

    Ghaname, Eduardo S; Ritter, André V; Heymann, Harald O; Vann, William F; Shugars, Daniel A; Bader, James D

    2010-02-01

    This study evaluated the correlation between laser fluorescence readings and the extent of incipient occlusal caries as measured by the volume of tooth preparation in vitro. One hundred and three permanent molars and premolars containing incipient occlusal pit-and-fissure caries and sound occlusal surfaces (1/4 of the sample, control) were selected. DIAGNOdent (KaVo Dental Corporation, Lake Zurich, IL, USA) readings were obtained according to manufacturer instructions. Caries was removed with 1/4 round burs in high speed. The volume of tooth preparation was measured using a surrogate measure based on the amount of composite needed to fill the preparations. Sensitivity and specificity using different cutoff values were calculated for lesions/preparations extending into dentin. The results were analyzed statistically. The Pearson correlation for preparation volume and DIAGNOdent reading measurements was low (r = 0.285). Sensitivity and specificity of DIAGNOdent for detection of dentinal lesions were 0.83 and 0.60, and 0.66 and 0.73 for the cutoff values of 20 and 30, respectively. Within the limitations of this study, laser fluorescence measured with DIAGNOdent does not correlate well with extent of carious tooth structure in incipient occlusal caries. Clinicians should not rely only on DIAGNOdent readings to determine the extension of incipient occlusal caries.

  20. Incipient merger of Cls 11 and 5 in Xhosa? | Gowlett | South African ...

    African Journals Online (AJOL)

    In Xhosa, there appears to be an incipient merger between Noun Classes 5 and 11, as revealed by frequent mismatches between Cl. 11 nouns and various concordial elements, and even the replacement of the Cl. 11 noun prefix by that of Cl. 5. In this article we explore possible reasons for this putative merger, and present ...

  1. Transformer Incipient Fault Prediction Using Combined Artificial Neural Network and Various Particle Swarm Optimisation Techniques.

    Directory of Open Access Journals (Sweden)

    Hazlee Azil Illias

    Full Text Available It is important to predict the incipient fault in transformer oil accurately so that the maintenance of transformer oil can be performed correctly, reducing the cost of maintenance and minimise the error. Dissolved gas analysis (DGA has been widely used to predict the incipient fault in power transformers. However, sometimes the existing DGA methods yield inaccurate prediction of the incipient fault in transformer oil because each method is only suitable for certain conditions. Many previous works have reported on the use of intelligence methods to predict the transformer faults. However, it is believed that the accuracy of the previously proposed methods can still be improved. Since artificial neural network (ANN and particle swarm optimisation (PSO techniques have never been used in the previously reported work, this work proposes a combination of ANN and various PSO techniques to predict the transformer incipient fault. The advantages of PSO are simplicity and easy implementation. The effectiveness of various PSO techniques in combination with ANN is validated by comparison with the results from the actual fault diagnosis, an existing diagnosis method and ANN alone. Comparison of the results from the proposed methods with the previously reported work was also performed to show the improvement of the proposed methods. It was found that the proposed ANN-Evolutionary PSO method yields the highest percentage of correct identification for transformer fault type than the existing diagnosis method and previously reported works.

  2. Incipient ovarian failure and premature ovarian failure show the same immunological profile

    NARCIS (Netherlands)

    van Kasteren, YM; von Blomberg, M; Hoek, A; de Koning, C; Lambalk, N; van Montfrans, J; Kuik, J

    PROBLEM: Incipient ovarian failure (IOF) is characterized by regular menstrual cycles, infertility and a raised early-follicular FSH in women under 40. IOF might be a precursor or a mitigated form of premature ovarian failure (POF). Disturbances in the immune system may play a role in ovarian

  3. Abnormal albuminuria and blood pressure rise in incipient diabetic nephropathy induced by exercise

    DEFF Research Database (Denmark)

    Christensen, Cramer

    1984-01-01

    The aim of the study was to evaluate the influence of light to moderate dynamic work (450 kpm/min followed by 600 kpm/min during 20 min each) on the blood pressure and renal protein handling in insulin-dependent diabetic patients with incipient nephropathy (D3) (elevated baseline albumin excretio...

  4. CSF biomarkers and incipient Alzheimer disease in patients with mild cognitive impairment.

    NARCIS (Netherlands)

    Mattsson, N.; Zetterberg, H.; Hansson, O.; Andreasen, N.; Parnetti, L.; Jonsson, M.; Herukka, S.K.; Flier, W.M. van der; Blankenstein, M.A.; Ewers, M.; Rich, K.; Kaiser, E.; Verbeek, M.M.; Tsolaki, M.; Mulugeta, E.; Rosen, E.; Aarsland, D.; Visser, P.J.; Schroder, J.; Marcusson, J.; Leon, M.; Hampel, H.; Scheltens, P.; Pirttilä, T.; Wallin, A.; Jonhagen, M.E.; Minthon, L.; Winblad, B.; Blennow, K.

    2009-01-01

    CONTEXT: Small single-center studies have shown that cerebrospinal fluid (CSF) biomarkers may be useful to identify incipient Alzheimer disease (AD) in patients with mild cognitive impairment (MCI), but large-scale multicenter studies have not been conducted. OBJECTIVE: To determine the diagnostic

  5. Incipient ferroelectric properties of NaTaO.sub.3./sub

    Czech Academy of Sciences Publication Activity Database

    Kamba, Stanislav; Goian, Veronica; Bovtun, Viktor; Nuzhnyy, Dmitry; Kempa, Martin; Spreitzer, M.; König, J.; Suvorov, D.

    2012-01-01

    Roč. 426, SI (2012), s. 206-214 ISSN 0015-0193 R&D Projects: GA ČR(CZ) GA202/09/0682 Institutional research plan: CEZ:AV0Z10100520 Keywords : incipient ferroelectricity * infrared and THz spectroscopy * phonons * microwave ceramics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.415, year: 2012

  6. Influence of decelerating flow on incipient motion of a gravel-bed ...

    Indian Academy of Sciences (India)

    Influence of decelerating flow on incipient motion of a gravel-bed stream. HOSSEIN AFZALIMHR. ∗,1. , SUBHASISH DEY. 2 and. POONEH RASOULIANFAR. 1. 1Department of Water Engineering, Isfahan University of Technology, Isfahan, Iran. 2Department of Civil Engineering, Indian Institute of Technology,. Kharagpur ...

  7. Transformer Incipient Fault Prediction Using Combined Artificial Neural Network and Various Particle Swarm Optimisation Techniques

    Science.gov (United States)

    2015-01-01

    It is important to predict the incipient fault in transformer oil accurately so that the maintenance of transformer oil can be performed correctly, reducing the cost of maintenance and minimise the error. Dissolved gas analysis (DGA) has been widely used to predict the incipient fault in power transformers. However, sometimes the existing DGA methods yield inaccurate prediction of the incipient fault in transformer oil because each method is only suitable for certain conditions. Many previous works have reported on the use of intelligence methods to predict the transformer faults. However, it is believed that the accuracy of the previously proposed methods can still be improved. Since artificial neural network (ANN) and particle swarm optimisation (PSO) techniques have never been used in the previously reported work, this work proposes a combination of ANN and various PSO techniques to predict the transformer incipient fault. The advantages of PSO are simplicity and easy implementation. The effectiveness of various PSO techniques in combination with ANN is validated by comparison with the results from the actual fault diagnosis, an existing diagnosis method and ANN alone. Comparison of the results from the proposed methods with the previously reported work was also performed to show the improvement of the proposed methods. It was found that the proposed ANN-Evolutionary PSO method yields the highest percentage of correct identification for transformer fault type than the existing diagnosis method and previously reported works. PMID:26103634

  8. Experimental investigation of mantle melting in the presence of carbonates

    Science.gov (United States)

    Dasgupta, Rajdeep

    High pressure-temperature experiments are performed at pressures of 2 to 10 GPa and temperatures of 900 to 1600 °C to constrain partial melting of carbonate bearing mantle eclogite and peridotite. Eclogite and peridotite in the presence of CO2 is observed to produce carbonatitic melts at their respective solidi for most parts of Earth's upper mantle. The solidus of carbonated eclogite at 3 GPa is observed to vary significantly with bulk Ca/Mg and Na2O content. But the appropriate solidus of carbonated ocean crust remains hotter than the subduction geotherms up to 260 km, indicating subduction of carbon, in the form of magnesite-eclogite, deep into the mantle. Upwelling mantle eclogite, on the other hand, must release carbonatite at depths >350 km. From experiments at 3 GPa, it is found that carbonated eclogite can generate silicate partial melts that can give rise to silica-undersaturated ocean island lavas. Solidus of carbonated peridotite from 3 to 10 GPa indicates that along an oceanic geotherm, the onset of partial melting happens shallower than that of carbonated eclogite, but still as deep as 300-330 km beneath ridges. Extraction of incipient carbonatite from deep mantle implies efficient removal of highly incompatible trace elements, including carbon, from the mantle. This deep melting likely creates a vast mantle residue that is depleted and fractionated in important trace elements and also might explain many geophysical features of Earth's deep upper mantle. Experiments with peridotite of variable carbonate concentrations also indicate that increasing CO2, unlike H2O, does not cause the isobaric solidus of carbonated peridotite to decrease. Using a new method of iterative sandwich experiments, the detailed composition of near-solidus melt from carbonated peridotite is determined at 6.6 GPa. Near-solidus melt of peridotite + CO2 at a depth of ˜200 km is Fe-Na bearing magnesio-dolomitic carbonatite. Transition from near-solidus carbonatite to carbonated

  9. On the effect of cross sectional shape on incipient motion and deposition of sediments in fixed bed channels

    Directory of Open Access Journals (Sweden)

    Safari Mir-Jafar-Sadegh

    2014-03-01

    Full Text Available The condition of incipient motion and deposition are of the essential issues for the study of sediment transport. This phenomenon is of great importance to hydraulic engineers for designing sewers, drainage, as well as other rigid boundary channels. This is a study carried out with the objectives of describing the effect of cross-sectional shape on incipient motion and deposition of particles in rigid boundary channels. In this research work, the experimental data given by Loveless (1992 and Mohammadi (2005 are used. On the basis of the critical velocity approach, a new incipient motion equation for a V-shaped bottom channel and incipient deposition of sediment particles equations for rigid boundary channels having circular, rectangular, and U-shaped cross sections are obtained. New equations were compared to the other incipient motion equations. The result shows that the cross-sectional shape is an important factor for defining the minimum velocity for no-deposit particles. This study also distinguishes incipient motion of particles from incipient deposition for particles. The results may be useful for designing fixed bed channels with a limited deposition condition.

  10. Observation of a prewetting transition during surface melting of caprolactam

    Science.gov (United States)

    Chandavarkar, Sumant; Geertman, Rob M.; de Jeu, Wim H.

    1992-10-01

    The surface-induced melting of the closed-packed (100) face of the anisotropic molecular crystal caprolactam has been studied using x-ray reflectivity. A thin-to-thick film prewetting transition is observed at about 13 K below the bulk melting point. Only above this transition does the thickness of the quasiliquid layer increase continuously with temperature. We speculate that initially the surface melting proceeds via layering transitions.

  11. Melt Cast High Explosives

    Directory of Open Access Journals (Sweden)

    Stanisław Cudziło

    2014-12-01

    Full Text Available [b]Abstract[/b]. This paper reviews the current state and future developments of melt-cast high explosives. First the compositions, properties and methods of preparation of trinitrotoluene based (TNT conventional mixtures with aluminum, hexogen (RDX or octogen (HMX are described. In the newer, less sensitive explosive formulations, TNT is replaced with dinitroanisole (DNANDNANDNAN and nitrotriazolone (NTONTONTO, nitroguanidine (NG or ammonium perchlorate (AP are the replacement for RDRDX and HMX. Plasticized wax or polymer-based binder systems for melt castable explosives are also included. Hydroxyl terminated polybutadiene (HPTB is the binder of choice, but polyethylene glycol, and polycaprolactone with energetic plasticizers are also used. The most advanced melt-cast explosives are compositions containing energetic thermoplastic elastomers and novel highly energetic compounds (including nitrogen rich molecules in whose particles are nanosized and practically defect-less.[b]Keywords[/b]: melt-cast explosives, detonation parameters

  12. Sensitivity of gap symmetry to an incipient band: Application to iron based superconductors

    Science.gov (United States)

    Mishra, Vivek; Scalapino, Douglas; Maier, Thomas

    Observation of high temperature superconductivity in iron-based superconductors with a submerged hole band has attracted wide interest. A spin fluctuation mediated pairing mechanism has been proposed as a possible explanation for the high transition temperatures observed in these systems. Here we discuss the importance of the submerged band in the context of the gap symmetry. We show that the incipient band can lead to an attractive pairing interaction and thus have significant effects on the pairing symmetry. We propose a framework to include the effect of the incipient band in the standard multi-orbital spin-fluctuation theories which are widely used for studying various iron-based superconductors. Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy.

  13. A New MLP Approach for the Detection of the Incipient Bearing Damage

    Directory of Open Access Journals (Sweden)

    SEKER, S.

    2010-08-01

    Full Text Available In this study, it is aimed to track the aging trend of the incipient bearing damage in an induction motor which is subjected to an accelerated aging process. For this purpose, a new Multilayer perceptron (MLP neural network approach is introduced. The input signals are extracted from power spectral densities (PSD of the vibration signals taken from a 5-HP induction motor. Principal component analysis (PCA has been applied to select the best possible feature vectors as a dimensionality reduction purpose. Variance and entropy values are used as the targets of the MLP network. The healthy motor condition was modelled by the MLP network considering all load conditions. The results showed that the incipient bearing damage was clearly extracted by the oscillations of the MLP output error.

  14. Early diagnosis of incipient caries based on non-invasive lasers

    Science.gov (United States)

    Velescu, A.; Todea, C.; Vitez, B.

    2016-03-01

    AIM: The aim of this study is to detect incipient caries and enamel demineralization using laser fluorescence.This serves only as an auxilary aid to identify and to monitor the development of these lesions. MATERIALS AND METHODS: 6 patients were involved in this study, three females and three male. Each patient underwent a professional cleaning, visual examination of the oral cavity, and then direct inspection using DiagnoCam and DIAGNOdent. After data recording each patient was submitted to retro-alveolar X-ray on teeth that were detected with enamel lesions. All data was collected and analyzed statistically. RESULTS: Of 36 areas considered in clinically healthy, 24 carious surfaces were found using laser fluorescence, a totally non-invasive method for detecting incipient carious lesions compared with the radiographic examination. CONCLUSIONS: This method has good applicability for patients because it improves treatment plan by early detection of caries and involves less fear for anxious patients and children.

  15. Melt fracture revisited

    Energy Technology Data Exchange (ETDEWEB)

    Greenberg, J. M.

    2003-07-16

    In a previous paper the author and Demay advanced a model to explain the melt fracture instability observed when molten linear polymer melts are extruded in a capillary rheometer operating under the controlled condition that the inlet flow rate was held constant. The model postulated that the melts were a slightly compressible viscous fluid and allowed for slipping of the melt at the wall. The novel feature of that model was the use of an empirical switch law which governed the amount of wall slip. The model successfully accounted for the oscillatory behavior of the exit flow rate, typically referred to as the melt fracture instability, but did not simultaneously yield the fine scale spatial oscillations in the melt typically referred to as shark skin. In this note a new model is advanced which simultaneously explains the melt fracture instability and shark skin phenomena. The model postulates that the polymer is a slightly compressible linearly viscous fluid but assumes no slip boundary conditions at the capillary wall. In simple shear the shear stress {tau}and strain rate d are assumed to be related by d = F{tau} where F ranges between F{sub 2} and F{sub 1} > F{sub 2}. A strain rate dependent yield function is introduced and this function governs whether F evolves towards F{sub 2} or F{sub 1}. This model accounts for the empirical observation that at high shears polymers align and slide more easily than at low shears and explains both the melt fracture and shark skin phenomena.

  16. Survey of the current state of knowledge of incipient boiling superheat in sodium

    International Nuclear Information System (INIS)

    Greer, B.

    1979-01-01

    Superheat data obtained by various investigators indicate that many parameters affect this phenomenon. Controlling parameters appear to be inert gas concentration, oxide concentration, system pressure, pressure-temperature history, rate of temperature rise, heat flux, flow rate, operating time on the system, surface conditions, and radiation. Of these, the two believed most influential in controlling incipient boiling superheat are the inert gas concentration and oxide concentration. Experimental results for the heat flux and rate of temperature rise appear to be the most inconsistent

  17. Near-infrared hyperspectral imaging of water evaporation dynamics for early detection of incipient caries.

    Science.gov (United States)

    Usenik, Peter; Bürmen, Miran; Fidler, Aleš; Pernuš, Franjo; Likar, Boštjan

    2014-10-01

    Incipient caries is characterized as demineralization of the tooth enamel reflecting in increased porosity of enamel structure. As a result, the demineralized enamel may contain increased amount of water, and exhibit different water evaporation dynamics than the sound enamel. The objective of this paper is to assess the applicability of water evaporation dynamics of sound and demineralized enamel for detection and quantification of incipient caries using near-infrared hyperspectral imaging. The time lapse of water evaporation from enamel samples with artificial and natural caries lesions of different stages was imaged by a near-infrared hyperspectral imaging system. Partial least squares regression was used to predict the water content from the acquired spectra. The water evaporation dynamics was characterized by a first order logarithmic drying model. The calculated time constants of the logarithmic drying model were used as the discriminative feature. The conducted measurements showed that demineralized enamel contains more water and exhibits significantly faster water evaporation than the sound enamel. By appropriate modelling of the water evaporation process from the enamel surface, the contrast between the sound and demineralized enamel observed in the individual near infrared spectral images can be substantially enhanced. The presented results indicate that near-infrared based prediction of water content combined with an appropriate drying model presents a strong foundation for development of novel diagnostic tools for incipient caries detection. The results of the study enhance the understanding of the water evaporation process from the sound and demineralized enamel and have significant implications for the detection of incipient caries by near-infrared hyperspectral imaging. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Radioactive waste melting furnace

    International Nuclear Information System (INIS)

    Nakayama, Junpei.

    1997-01-01

    The present invention provides a radioactive waste melting furnace excellent in heat insulating property, capable of exchanging only refractory materials with lesser amount of contamination. Namely, an heat insulation layer is disposed on the outer wall of the melting furnace. A refractory layer is disposed on the inner wall being in contact with molten materials in the melting furnace. A metal vessel covering the refractory layer is interposed between the heat insulation layer and the refractory layer. In addition, a metal outer shell covering the heat insulation layer is disposed on the heat insulation layer on the outer wall of the melting furnace. Bricks comprising, for example, alumina, carbon, zircon, magnesia or chromia having a low heat conductivity are used for the outer wall heat insulation layer irrespective of the melting performance. The refractory layer on the inner wall is made of bricks comprising chromia, alumina and zircon as molten materials of low basicity and chromia and magnesia as molten materials of high basicity. The materials of the metal vessel may be ordinary carbon steels, cast irons, or stainless steels. The refractory layer is taken out from the melting furnace together with the metal vessel, and only the refractory layer can be removed. Radiation contamination is eliminated. The metal vessel can be used again. (I.S.)

  19. Acoustic Emission Monitoring of Incipient in Journal Bearings - Part I : Detectability and measurement for bearing damages

    International Nuclear Information System (INIS)

    Yoon, Dong Jin; Kwon, Oh Yang; Chung, Min Hwa; Kim, Kyung Woong

    1994-01-01

    In contrast to the machinery using rolling element bearings, systems with journal bearings generally operate in large scale and under severe loading condition such as steam generator turbines and internal combustion engines. Failure of the bearings in these machinery can result in the system breakdown. To avoid the time consuming repair and considerable economic loss, the detection of incipient failure in journal bearings becomes very important. In this experimental approach, acoustic emission monitoring is applied to the detection of incipient failure caused by several types of abnormal operating condition most probable in the journal bearing systems. It has been known that the intervention of foreign materials, insufficient lubrication and misassembly etc. are principal factors to cause bearing failure and distress. The experiment was conducted under such designed conditions as hard particles in the lubrication layer, insufficient lubrication, and metallic contact in the simulated journal bearing system. The results showed that acoustic emission could be an effective tool to detect the incipient failure in journal bearings

  20. Incipient multiple fault diagnosis in real time with applications to large-scale systems

    International Nuclear Information System (INIS)

    Chung, H.Y.; Bien, Z.; Park, J.H.; Seon, P.H.

    1994-01-01

    By using a modified signed directed graph (SDG) together with the distributed artificial neutral networks and a knowledge-based system, a method of incipient multi-fault diagnosis is presented for large-scale physical systems with complex pipes and instrumentations such as valves, actuators, sensors, and controllers. The proposed method is designed so as to (1) make a real-time incipient fault diagnosis possible for large-scale systems, (2) perform the fault diagnosis not only in the steady-state case but also in the transient case as well by using a concept of fault propagation time, which is newly adopted in the SDG model, (3) provide with highly reliable diagnosis results and explanation capability of faults diagnosed as in an expert system, and (4) diagnose the pipe damage such as leaking, break, or throttling. This method is applied for diagnosis of a pressurizer in the Kori Nuclear Power Plant (NPP) unit 2 in Korea under a transient condition, and its result is reported to show satisfactory performance of the method for the incipient multi-fault diagnosis of such a large-scale system in a real-time manner

  1. Incipient toxicity of lithium to freshwater organisms representing a salmonid habitat

    International Nuclear Information System (INIS)

    Emery, R.; Klopfer, D.C.; Skalski, J.R.

    1981-07-01

    Because the eventual development of fusion power reactors could increase the mining, use and disposal of lithium five-fold by the year 2000, potential effects from unusual amounts of lithium in aquatic environments were investigated. Freshwater oganisms representing a Pacific Northwest salmonid habitat were exposed to elevated conentrations of lithium. Nine parameters were used to determine the incipient toxicity of lithium to rainbow trout (Salmo gairdneri), insect larvae (Chironomus sp.), and Columbia River periphyton. All three groups of biota were incipiently sensitive to lithium at concentrations ranging between 0.1 and 1 mg/L. These results correspond with the incipient toxicity of beryllium, a chemically similar component of fusion reactor cores. A maximum lithium concentration of 0.01 mg/L occurs naturally in most freshwater environments (beryllium is rarer). Therefore, a concentration range of 0.01 to 0.1 mg/L may be regarded as approaching toxic concentrations when assessing the hazards of lithium in freshwaters

  2. Incipient toxicity of lithium to freshwater organisms representing a salmonid habitat

    Energy Technology Data Exchange (ETDEWEB)

    Emery, R.; Klopfer, D.C.; Skalski, J.R.

    1981-07-01

    Because the eventual development of fusion power reactors could increase the mining, use and disposal of lithium five-fold by the year 2000, potential effects from unusual amounts of lithium in aquatic environments were investigated. Freshwater oganisms representing a Pacific Northwest salmonid habitat were exposed to elevated conentrations of lithium. Nine parameters were used to determine the incipient toxicity of lithium to rainbow trout (Salmo gairdneri), insect larvae (Chironomus sp.), and Columbia River periphyton. All three groups of biota were incipiently sensitive to lithium at concentrations ranging between 0.1 and 1 mg/L. These results correspond with the incipient toxicity of beryllium, a chemically similar component of fusion reactor cores. A maximum lithium concentration of 0.01 mg/L occurs naturally in most freshwater environments (beryllium is rarer). Therefore, a concentration range of 0.01 to 0.1 mg/L may be regarded as approaching toxic concentrations when assessing the hazards of lithium in freshwaters.

  3. [Preventive and remineralization effect over incipient lesions of caries decay by phosphopeptide-amorphous calcium phosphate].

    Science.gov (United States)

    Juárez-López, María Lilia Adriana; Hernández-Palacios, Rosa Diana; Hernández-Guerrero, Juan Carlos; Jiménez-Farfán, Dolores; Molina-Frechero, Nelly

    2014-01-01

    INTRODUCTION. Dental caries continues to affect a large percentage of Mexican children and currently advises that if diagnosed at an early stage can be reversed with minimally invasive treatments. The casein phosphopeptide amorphous calcium phosphate known as CPP-ACP is a phosphoprotein capable of releasing calcium and phosphate ions in the oral environment promoting remineralization. OBJECTIVE. To evaluate the effect of CPP-ACP with fluoride added in a scholar preventive program. MATERIAL AND METHODS. A cuasi- experimental study was conducted in 104 schools of six years old. The children were classified into three groups and received six months biweekly applications of different treatments: casein phosphopeptide amorphous calcium phosphate added fluoride (CPP-ACPF), sodium fluoride (NaF) and a control group. Clinical evaluation was performed with the laser fluorescence technique (Diagnodent model 2095). 1340 teeth were included: 294 teeth with incipient lesions and 1,046 healthy teeth. Statistical tests of χ2 y Mc Nemar were used. RESULTS. In the group that received the application of CPP-ACPF, 38% of incipient carious lesions were remineralizing compared with 21% in the group receiving the NaF (p application biweekly for six months of CPP-ACPF showed a protective and remineralizing effect on incipient carious lesions. His action was better than the application of NaF. However, to reduce the impact from dental caries in schoolchildren is important to have a comprehensive preventive approach that includes promoting self-care, as well as the application of sealants.

  4. Multiple incipient sensor faults diagnosis with application to high-speed railway traction devices.

    Science.gov (United States)

    Wu, Yunkai; Jiang, Bin; Lu, Ningyun; Yang, Hao; Zhou, Yang

    2017-03-01

    This paper deals with the problem of incipient fault diagnosis for a class of Lipschitz nonlinear systems with sensor biases and explores further results of total measurable fault information residual (ToMFIR). Firstly, state and output transformations are introduced to transform the original system into two subsystems. The first subsystem is subject to system disturbances and free from sensor faults, while the second subsystem contains sensor faults but without any system disturbances. Sensor faults in the second subsystem are then formed as actuator faults by using a pseudo-actuator based approach. Since the effects of system disturbances on the residual are completely decoupled, multiple incipient sensor faults can be detected by constructing ToMFIR, and the fault detectability condition is then derived for discriminating the detectable incipient sensor faults. Further, a sliding-mode observers (SMOs) based fault isolation scheme is designed to guarantee accurate isolation of multiple sensor faults. Finally, simulation results conducted on a CRH2 high-speed railway traction device are given to demonstrate the effectiveness of the proposed approach. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  5. MELTED BUTTER TECHNOLOGY DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    L. V. Golubeva

    2014-01-01

    Full Text Available Summary. Melted butter is made from dairy butter by rendering the fat phase. It has specific taste and aroma, high-calorie content and good assimilability. Defects of butter which appeared during the storage causes by the development of microbiological processes or by the chemical oxidation. On the development of these processes influence quality and composition of fresh butter, its physical structure, content of the increased amount of gas phase and content of heavy metals, storage conditions. Microbiological spoilage of butter occurs generally due to damage of plasma which is good environment for the development of microorganisms. Defects of microbiological origin include: unclean, sour, moldy, yeasty, cheesy, bitter taste. Defects of test and smell chemical origin are formed due to hydrolytic digestion of lipids. It's prevailed at long storage of butter in the conditions of freezing temperatures. It's picked out the following main processes of spoiling: souring, acidifying and sallowness. Often these processes take place simultaneously.It has been investigated melted butter with lactated additive. The latter improves the microbiological and toxicological safety, prolongs the storage condition of the products. Technological efficiency of the additives is achieved by a multilayer products formation from the inactive bound water, preventing microorganisms growth and by the barrier layer with lactate inhibiting hydrolytic reactions. Oil samples were obtained with the batch-type butter maker application, then they were melted and after that lactated additive were supplemented. It has been studied organoleptic and physico-chemical indices of the melted butter samples. The fatty-acid composition of melted butter were studied. Comparative analysis of fatty-acid composition of cow's milk fat and produced melted butter has shown their similarity. Also in the last sample there is increased weight fraction of linoleic and linolenic acids. The obtained

  6. Melting temperature of graphite

    International Nuclear Information System (INIS)

    Korobenko, V.N.; Savvatimskiy, A.I.

    2001-01-01

    Full Text: Pulse of electrical current is used for fast heating (∼ 1 μs) of metal and graphite specimens placed in dielectric solid media. Specimen consists of two strips (90 μm in thick) placed together with small gap so they form a black body model. Quasy-monocrystal graphite specimens were used for uniform heating of graphite. Temperature measurements were fulfilled with fast pyrometer and with composite 2-strip black body model up to melting temperature. There were fulfilled experiments with zirconium and tungsten of the same black body construction. Additional temperature measurements of liquid zirconium and liquid tungsten are made. Specific heat capacity (c P ) of liquid zirconium and of liquid tungsten has a common feature in c P diminishing just after melting. It reveals c P diminishing after melting in both cases over the narrow temperature range up to usual values known from steady state measurements. Over the next wide temperature range heat capacity for W (up to 5000 K) and Zr (up to 4100 K) show different dependencies of heat capacity on temperature in liquid state. The experiments confirmed a high quality of 2-strip black body model used for graphite temperature measurements. Melting temperature plateau of tungsten (3690 K) was used for pyrometer calibration area for graphite temperature measurement. As a result, a preliminary value of graphite melting temperature of 4800 K was obtained. (author)

  7. Granulite Migmatization and Retrogression: Result of Pervasive Melt Influx? (Invited)

    Science.gov (United States)

    Hasalova, P.; Štípská, P.; Weinberg, R. F.; Franěk, J.; Schulmann, K.

    2013-12-01

    The Blanský les granulite massif (BLG) is large (ca. 270 km2) lower crust exposure in Bohemian Massif in Czech Republic. It consists of felsic granulites in various degrees of retrogression and small bodies of eclogites, mafic granulites and ultrabasites. Peak granulitic conditions were estimated at ca. 16-18 kbar and 850-1100°C. This granulite massif was later, during exhumation, heterogeneously retrogressed in amphibolite facies conditions (ca. 5-7 kbar and 700-800°C). The degree of granulite retrogression increases continuously from the core towards the margin of the BLG massif. The question raised in this work is the nature of the retrogression. In core of the massif retrogression is manifested only by plagioclase and spinel coronas around kyanite. Towards the margin granulite gets progressively hydrated, has gneissic look and stable mineral assemblage of Qtz + Kfs + Pl + Bt + Sill × Grt. Retrograde granulite reveals higher amount of biotite, which forms at expanse of garnet and kyanite break down to sillimanite. Along the margin the transformation is accompanied by presence of melt, resulting into formation of migmatitic gneisses. The detailed field and microstructural observations revealed a gradual transition from mylonitic gneiss with only incipient amount of melt to migmatitic gneisses with no relict of gneissosity and high proportion of melt. This transition is accompanied by textural changes as well as changes in mineral chemistry (increase of XFe in biotite and garnet, increase of Na in plagioclase) and mineral proportions (decrease of garnet %, increase of biotite and feldspars %). During the exhumation, the granulite was dry, thus melt present in the granulite cannot be produced in-situ. We suggest that the hot dry granulite released and 'attracted' water from colder underlying metasedimentary sequence. This water flux caused extensive melting along the massif margins. This melt then further pervasively migrated towards the core of the massif

  8. 3He melting pressure temperature scale

    DEFF Research Database (Denmark)

    Halperin, W.P.; Archie, C.N.; Richardson, R.C.

    1976-01-01

    The latent heat for solidification of **3He has been measured along the **3He melting curve between 23 and 1 mK. A temperature scale is established which depends only on measurements of heat, pressure and volume, and on the condition that the entropy of solid **3He approaches R ln 2 at high...... temperatures. The A feature of the melting curve which suggests itself as a thermometric fixed point is found to be T//A equals 2. 75 plus or minus 0. 11 mK. The agreement between this value and independent measurements of T//A, based on nuclear or electronic paramagnetism, Johnson noise thermometry...

  9. Applications of nonequilibrium melting concept to damage-accumulation processes

    International Nuclear Information System (INIS)

    Lam, N.Q.; Okamoto, P.R.

    1998-01-01

    The authors recent study of crystalline-to-amorphous transformation led to the successful development of a unified thermodynamic description of disorder-induced amorphization and heat-induced melting, based on a generalized version of the Lindemann melting criterion. The generalized criterion requires that the melting temperature of a defective crystal decreases with increasing static atomic disorder. Hence, any crystal can melt at temperatures below the melting point of its perfect crystalline state when driven far from equilibrium by introducing critical amounts of misfitting solute atoms and lattice imperfections, radiation damage, and/or tensile stresses. This conceptual approach to nonequilibrium melting provides new insight into long-standing materials problems such as brittle fracture, embrittlement, and environmentally-induced cracking, for example irradiation-assisted stress corrosion cracking

  10. Applications of nonequilibrium melting concept to damage-accumulation processes

    Energy Technology Data Exchange (ETDEWEB)

    Lam, N.Q.; Okamoto, P.R.

    1998-01-01

    The authors recent study of crystalline-to-amorphous transformation led to the successful development of a unified thermodynamic description of disorder-induced amorphization and heat-induced melting, based on a generalized version of the Lindemann melting criterion. The generalized criterion requires that the melting temperature of a defective crystal decreases with increasing static atomic disorder. Hence, any crystal can melt at temperatures below the melting point of its perfect crystalline state when driven far from equilibrium by introducing critical amounts of misfitting solute atoms and lattice imperfections, radiation damage, and/or tensile stresses. This conceptual approach to nonequilibrium melting provides new insight into long-standing materials problems such as brittle fracture, embrittlement, and environmentally-induced cracking, for example irradiation-assisted stress corrosion cracking.

  11. In Situ Partial Melt on Venus: Evidence for Ancient Water?

    Science.gov (United States)

    Hansen, V. L.

    2003-03-01

    Shield terrain comprises countless tiny lava flows that coalesced to form an ultra-thin discontinuous regionally extensive mechanically strong layer; lava represents point-source crustal partial melt and may provide evidence for ancient Venus water.

  12. GLASS MELTING PHENOMENA, THEIR ORDERING AND MELTING SPACE UTILISATION

    Directory of Open Access Journals (Sweden)

    Němec L.

    2013-12-01

    Full Text Available Four aspects of effective glass melting have been defined – namely the fast kinetics of partial melting phenomena, a consideration of the melting phenomena ordering, high utilisation of the melting space, and effective utilisation of the supplied energy. The relations were defined for the specific melting performance and specific energy consumption of the glass melting process which involve the four mentioned aspects of the process and indicate the potentials of effective melting. The quantity “space utilisation” has been treated in more detail as an aspect not considered in practice till this time. The space utilisation was quantitatively defined and its values have been determined for the industrial melting facility by mathematical modelling. The definitions of the specific melting performance and specific energy consumption have been used for assessment of the potential impact of a controlled melt flow and high space utilisation on the melting process efficiency on the industrial scale. The results have shown that even the partial control of the melt flow, leading to the partial increase of the space utilisation, may considerably increase the melting performance, whereas a decrease of the specific energy consumption was determined to be between 10 - 15 %.

  13. Viscosity Measurement for Tellurium Melt

    Science.gov (United States)

    Lin, Bochuan; Li, Chao; Ban, Heng; Scripa, Rosalia N.; Su, Ching-Hua; Lehoczky, Sandor L.

    2006-01-01

    The viscosity of high temperature Te melt was measured using a new technique in which a rotating magnetic field was applied to the melt sealed in a suspended ampoule, and the torque exerted by rotating melt flow on the ampoule wall was measured. Governing equations for the coupled melt flow and ampoule torsional oscillation were solved, and the viscosity was extracted from the experimental data by numerical fitting. The computational result showed good agreement with experimental data. The melt velocity transient initiated by the rotating magnetic field reached a stable condition quickly, allowing the viscosity and electrical conductivity of the melt to be determined in a short period.

  14. MELT-IIIB: an updated version of the melt code

    International Nuclear Information System (INIS)

    Tabb, K.K.; Lewis, C.H.; O'Dell, L.D.; Padilla, A. Jr.; Smith, D.E.; Wilburn, N.P.

    1979-04-01

    The MELT series is a reactor modeling code designed to investigate a wide variety of hypothetical accident conditions, particularly the transient overpower sequence. MELT-IIIB is the latest in the series

  15. Melt electrospinning of biodegradable polyurethane scaffolds.

    Science.gov (United States)

    Karchin, Ari; Simonovsky, Felix I; Ratner, Buddy D; Sanders, Joan E

    2011-09-01

    Electrospinning from a melt, in contrast to from a solution, is an attractive tissue engineering scaffold manufacturing process as it allows for the formation of small diameter fibers while eliminating potentially cytotoxic solvents. Despite this, there is a dearth of literature on scaffold formation via melt electrospinning. This is likely due to the technical challenges related to the need for a well-controlled high-temperature setup and the difficulty in developing an appropriate polymer. In this paper, a biodegradable and thermally stable polyurethane (PU) is described specifically for use in melt electrospinning. Polymer formulations of aliphatic PUs based on (CH(2))(4)-content diisocyanates, polycaprolactone (PCL), 1,4-butanediamine and 1,4-butanediol (BD) were evaluated for utility in the melt electrospinning process. The final polymer formulation, a catalyst-purified PU based on 1,4-butane diisocyanate, PCL and BD in a 4/1/3M ratio with a weight-average molecular weight of about 40kDa, yielded a nontoxic polymer that could be readily electrospun from the melt. Scaffolds electrospun from this polymer contained point bonds between fibers and mechanical properties analogous to many in vivo soft tissues. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. Development of a custom-made "smart-sphere" to assess incipient entrainment by rolling

    Science.gov (United States)

    Valyrakis, Manousos; Kitsikoudis, Vasileios; Alexakis, Athanasios; Trinder, Jon

    2017-04-01

    The most widely applied criterion for sediment incipient motion in engineering applications is the time- and space-averaged approach of critical Shields shear stress. Nonetheless, in the recent years published research has highlighted the importance of turbulence fluctuations in sediment incipient motion and its stochastic character. The present experimental study investigates statistically the link of the response of a "smart-pebble" to hydrodynamics in near-critical flow conditions and discusses how such a device can be utilized in engineering design. A set of specifically designed fluvial experiments monitoring the entrainment conditions for a "smart-pebble", were carried out in a tilting, recirculating flume in turbulent flow conditions while three-dimensional flow measurements were obtained with an acoustic Doppler velocimeter. The "smart-pebble" employed herein is a custom-made instrumented sphere with 7 cm diameter, which has a number of sensors embedded within its waterproof 3D-printed plastic shell. Specifically, the "smart-pebble" is equipped with miniaturized, off the shelf, low-cost, three-dimensional acceleration, orientation and angular displacement sensors. A 3D-printed local micro topography of known geometry was installed in the flume's test section and the "smart-pebble" was placed there in order to facilitate the analysis. Every time the "smart-sphere" is displaced by the flow a downstream located pin blocks its full entrainment. This allows for continuous recording of the entrainment events due to the passage of energetic events, after which the "smart-pebble" returns to its resting pocket. The "smart-pebble" device under such a configuration allows the recording of normally indiscernible (with the naked eye) vibrations, twitching motions, and full entrainments for the studied particle, allowing its analysis from a Langrangian framework. During the incipient motion experiments the retrieved data are stored in an internal memory unit or

  17. Micro-topography controls on incipient motion in very steep, ephemeral streams

    Science.gov (United States)

    Scheingross, J. S.; Winchell, E. W.; Lamb, M. P.; Dietrich, W. E.

    2010-12-01

    Much of the drainage network in hilly and mountainous areas is composed of small, steep streams, and predicting incipient sediment motion in these streams is critical to modeling bedload transport, bedrock incision, and landscape evolution. While the conditions for incipient motion in low lying rivers have been well established, field measurements on initial motion in steep, mountainous streams remain sparse, and existing models remain relatively untested. To fill this knowledge gap, we monitored initial motion of sediment in six small (drainage areas of 0.05 - 2 km2) and steep (slopes of 3.5 - 35%) tributaries of the South Fork Eel River, CA. Sites were monitored for three winters from 2007 - 2010 using automated field cameras, water stage height recorders, and painted sediment. We calculated critical shear stress for grain entrainment using a number of methods including a 1D non-uniform hydraulic model (HEC-RAS), a normal flow model (i.e. τ = ρghS), and a form-drag-corrected model that accounts for immobile grains (i.e. Yager et al, 2007). In all cases, the available empirical and theoretical predictions do not adequately describe the observed transport. Furthermore, the data itself is highly scattered suggesting that the traditional non-dimensional framework used to describe incipient motion in low slope rivers (e.g. Shields number and relative grain roughness) may not adequately capture the physics of sediment transport in small, steep streams. We hypothesize that this discrepancy is due to centimeter-scale topographic variations and grain-size patchiness that appear to play an important role in controlling variations in sediment transport in these streams, especially at low-stage. Small steps and depressions within the channel bed create low-stage chutes and pools that result in highly variable flow velocities and basal shear stresses even within a single channel cross section. By changing shear stress distributions, these micro-topographic variations

  18. `Technology for Advanced Treatment of High Melting Point Metal-Based Material,` local research and development of important technology for fiscal 1997. Development of materials creation technology for high efficiency power generator components; 1997 nendo juyo chiiki gijutsu kenkyu kaihatsu. `Koyuten kinzokukei buzai no kodo kako gijutsu` (kokoritsu hatsuden`yo buzai sosei gijutsu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Efforts are made for the creation of high melting point metal-base materials to replace the currently-used Ni-base superalloys for the turbine to withstand higher operating temperatures. The main efforts made in fiscal 1997 are outlined. As in fiscal 1996, Nb-base solution alloys, in which solution reinforcement elements such as Mo and W are alloyed, are manufactured by button arc melting and tested for mechanical properties and texture/characteristics. In the designing and evaluation for a strongest Nb-base composite material, Nb-base composite materials are manufactured by use of particle dispersion-strengthening attained by addition of intermetallic compounds or elements to contribute to the formation of oxides, carbides, or nitrides. Nb-base composite materials may also be manufactured by use of eutectic-strengthening attained by utilizing crystallization in the process of coagulation. The resultant Nb-base composite materials are evaluated for their dynamic characteristics at high temperatures. In the development and evaluation of technologies for creating Nb-base materials for high-temperature components, larger specimens as heavy as several kg are tested in line with small specimens for basic studies, and the results are utilized for alloy designing for high-temperature materials. 50 refs., 97 figs., 15 tabs.

  19. Detecting incipient schizophrenia: a validation of the Azima battery in first episode psychosis.

    Science.gov (United States)

    Zafran, Hiba; Mazer, Barbara; Tallant, Beverlea; Chilingaryan, Gevorg; Gelinas, Isabelle

    2017-09-01

    Early psychosis intervention aims to accurately detect adolescents and young adults at risk for major mental disorders, particularly schizophrenia, yet early biomedical diagnostic accuracy remains poor. However, phenomenological approaches focusing on eliciting and understanding the subjective experience of help-seeking youth better detect incipient schizophrenia. The Azima Battery is an occupational therapy projective assessment that uses expressive media in a standard setup, in order to phenomenologically elicit and describe the activity performance and narratives of individuals at risk of, or on, the psychotic-spectrum.The purpose of this study was to estimate the predictive validity of the Azima Battery with youth seeking help for a first episode of psychosis, and identify patterns of performance distinctive of a diagnosis of schizophrenia 1-year later. A mixed methods phenomenological approach was used to calculate the predictive validity of the Azima Battery in detecting incipient schizophrenia, and to qualitatively identify patterns of performance. Study results demonstrate that the diagnostic accuracy of the Azima Battery is greater than psychiatric interviewing for a future diagnosis of schizophrenia (N = 62: 88.7 % vs 42 %). Performance elements and patterns statistically distinctive of schizophrenia are described, and relate to the structure of the created objects. Therefore, the Azima Battery is a valid measure for clinical use by occupational therapists working in early intervention for psychosis as a complement to traditional psychiatric interviewing.

  20. Evaluation of CO2 laser irradiation effect on enamel microhardness after incipient caries creation

    Directory of Open Access Journals (Sweden)

    Loghman Rezaei-Soufi

    2016-12-01

    Full Text Available Objective: The important mission in modern science of caries prevention is identification and providing the necessary actions for caries prevention to patients with an elevated risk of caries. The aim of this study was evaluation of CO2 laser irradiation effect on enamel microhardness after incipient caries creation. Material and methods: In this in vitro-experimental study, for evaluation of enamel microhardness 30 teeth after disinfection process were divided randomly into three groups A, B, C [n=10]: A] Control [normal saline] B] Immersed in cariogenic solution for 1 month C] Immersed in cariogenic solution for 1 month + CO2 laser [10.6µm, 10Hz, 0.5W, 20s, beam diameter 0.2 mm]. Data analyzing was used by 16 SPSS software. Parametric one-way ANOVA and Tukey were used for surface microhardness at 0.05% significance level. Results: According to one-way ANOVA parametric test, there was a significant difference between three groups [p=0.047]. In the following, results of Tukey test showed that there was a significant statistical difference between the microhardness of control and other groups [P=0.038]. On the other hand, there wasn’t statistical difference between A, C and B, C group means [P>0.05]. Conclusion: These study findings showed that CO2 laser irradiation on enamel surface with incipient caries had no significant effect on surface microhardness enhancement.

  1. Velocity-based analysis of sediment incipient deposition in rigid boundary open channels.

    Science.gov (United States)

    Aksoy, Hafzullah; Safari, Mir Jafar Sadegh; Unal, Necati Erdem; Mohammadi, Mirali

    2017-11-01

    Drainage systems must be designed in a way to minimize undesired problems such as decrease in hydraulic capacity of the channel, blockage and transport of pollutants due to deposition of sediment. Channel design considering self-cleansing criteria are used to solve the sedimentation problem. Incipient deposition is one of the non-deposition self-cleansing design criteria that can be used as a conservative method for channel design. Experimental studies have been carried out in five different cross-section channels, namely trapezoidal, rectangular, circular, U-shape and V-bottom. Experiments were performed in a tilting flume using four different sizes of sands as sediment in nine different channel bed slopes. Two well-known methods, namely the Novak & Nalluri and Yang methods are considered for the analysis of sediment motion. Equations developed using experimental data are found to be in agreement with the literature. It is concluded that the design velocity depends on the shape of the channel cross-section. Rectangular and V-bottom channels need lower and higher incipient deposition velocities, respectively, in comparison with other channels.

  2. Adaptive divergence with gene flow in incipient speciation of Miscanthus floridulus / sinensis complex (Poaceae)

    KAUST Repository

    Huang, Chao-Li

    2014-11-11

    Young incipient species provide ideal materials for untangling the process of ecological speciation in the presence of gene flow. The Miscanthus floridulus/sinensis complex exhibits diverse phenotypic and ecological differences despite recent divergence (approximately 1.59million years ago). To elucidate the process of genetic differentiation during early stages of ecological speciation, we analyzed genomic divergence in the Miscanthus complex using 72 randomly selected genes from a newly assembled transcriptome. In this study, rampant gene flow was detected between species, estimated as M=3.36x10(-9) to 1.20x10(-6), resulting in contradicting phylogenies across loci. Nevertheless, beast analyses revealed the species identity and the effects of extrinsic cohesive forces that counteracted the non-stop introgression. As expected, early in speciation with gene flow, only 3-13 loci were highly diverged; two to five outliers (approximately 2.78-6.94% of the genome) were characterized by strong linkage disequilibrium, and asymmetrically distributed among ecotypes, indicating footprints of diversifying selection. In conclusion, ecological speciation of incipient species of Miscanthus probably followed the parapatric model, whereas allopatric speciation cannot be completely ruled out, especially between the geographically isolated northern and southern M.sinensis, for which no significant gene flow across oceanic barriers was detected. Divergence between local ecotypes in early-stage speciation began at a few genomic regions under the influence of natural selection and divergence hitchhiking that overcame gene flow.

  3. Ecosystem Composition Controls the Fate of Rare Earth Elements during Incipient Soil Genesis

    Science.gov (United States)

    Zaharescu, Dragos G.; Burghelea, Carmen I.; Dontsova, Katerina; Presler, Jennifer K.; Maier, Raina M.; Huxman, Travis; Domanik, Kenneth J.; Hunt, Edward A.; Amistadi, Mary K.; Gaddis, Emily E.; Palacios-Menendez, Maria A.; Vaquera-Ibarra, Maria O.; Chorover, Jon

    2017-02-01

    The rare earth elements (REE) are increasingly important in a variety of science and economic fields, including (bio)geosciences, paleoecology, astrobiology, and mining. However, REE distribution in early rock-microbe-plant systems has remained elusive. We tested the hypothesis that REE mass-partitioning during incipient weathering of basalt, rhyolite, granite and schist depends on the activity of microbes, vascular plants (Buffalo grass), and arbuscular mycorrhiza. Pore-water element abundances revealed a rapid transition from abiotic to biotic signatures of weathering, the latter associated with smaller aqueous loss and larger plant uptake. Abiotic dissolution was 39% of total denudation in plant-microbes-mycorrhiza treatment. Microbes incremented denudation, particularly in rhyolite, and this resulted in decreased bioavailable solid pools in this rock. Total mobilization (aqueous + uptake) was ten times greater in planted compared to abiotic treatments, REE masses in plant generally exceeding those in water. Larger plants increased bioavailable solid pools, consistent with enhanced soil genesis. Mycorrhiza generally had a positive effect on total mobilization. The main mechanism behind incipient REE weathering was carbonation enhanced by biotic respiration, the denudation patterns being largely dictated by mineralogy. A consistent biotic signature was observed in La:phosphate and mobilization: solid pool ratios, and in the pattern of denudation and uptake.

  4. Melting graft wound syndrome

    Directory of Open Access Journals (Sweden)

    Shiou-Mei Chen

    2017-09-01

    Full Text Available Melting graft wound syndrome is characterized by progressive epidermal loss from a previously well-taken skin graft, healed burn, or donor site. It may result in considerable morbidity and require prolonged treatment. We report a 23-year-old flame-burned patient with second- to third-degree burns involving more than 70% of the total body surface area, whose condition was complicated with septic shock. The patient presented with erosions and ulcers occurring on previously well-taken skin graft recipient sites over both legs and progressive epidermal loss on donor sites over the back. The patient's presentation was compatible with the diagnosis of melting graft wound syndrome, and we successfully treated the patient with debridement and supportive treatment.

  5. Acute and long-term effect of antihypertensive treatment on exercise-induced albuminuria in incipient diabetic nephropathy

    DEFF Research Database (Denmark)

    Christensen, Cramer; Mogensen, C E

    1986-01-01

    . In the acute study, using placebo/metoprolol 10 mg i.v. in patients with normal UAE, the maximal SBP at 600 kpm/min was reduced by 17 mmHg +/- 10 (SD) (2p less than 1.0%) and the maximal SBP at 600 kpm/min in the patients with incipient nephropathy was reduced by 15 mmHg +/- 11 (SD) (2p less than 1.......0%). However, no difference was observed in UAE, in patients with normal UAE or those with incipient nephropathy. Five of the patients with incipient nephropathy were followed with repeated exercise tests before and during 2.6 years of antihypertensive treatment, using metoprolol 200 mg/24 h and subsequently...

  6. Review of candidate methods for detecting incipient defects due to aging of installed cables in nuclear power plants

    International Nuclear Information System (INIS)

    Martzloff, F.D.

    1988-01-01

    Several types of test methods have been proposed for detecting incipient defects due to aging in cable insulation systems, none offering certainty of detecting all possible types of defects. Some methods apply direct detection of a defect in the cable; other methods detect changes in electrical or non-electrical parameters from which inference can be drawn on the integrity of the cable. The paper summarizes the first year of a program conducted at the National Bureau of Standards to assess the potential of success for in situ detection of incipient defects by the most promising of these methods

  7. Mechanical properties of melt-derived erbium oxide

    International Nuclear Information System (INIS)

    Neuman, A.D.; Blacic, M.J.; Platero, M.; Romero, R.S.; McClellan, K.J.; Petrovic, J.J.

    1998-01-01

    Erbium oxide (Er 2 O 3 ) is a rare earth oxide that is chemically and thermally stable and has a melting point of 2,430 C. There is relatively little information available regarding single crystal growth of erbia or the properties of erbia. In this study, erbia single crystals have been grown in a Xenon Optical Floating Zone Unit (XeOFZ) capable of melting materials at temperatures up to 3,000 C. Erbia was melt synthesized in the XeOFZ unit in a container less fashion, proving for little chance of contamination. Crystals were grown in compressed air and in reducing atmospheres. A recurring problem with melt synthesis of erbia is the appearance of flakes at the edges of the melt zone during growth; these flakes disrupt the growth process. The processing details and an initial survey of the physical properties of erbia single crystals is discussed

  8. Emerging melt quality control solution technologies for aluminium melt

    Directory of Open Access Journals (Sweden)

    Arturo Pascual, Jr

    2009-11-01

    Full Text Available The newly developed “MTS 1500” Melt Treatment System is performing the specifi cally required melt treatment operations like degassing, cleaning, modification and/or grain refinement by an automated process in one step and at the same location. This linked process is saving time, energy and metal losses allowing - by automated dosage of the melt treatment agents - the production of a consistent melt quality batch after batch. By linking the MTS Metal Treatment System with sensors operating on-line in the melt, i.e., with a hydrogen sensor “Alspek H”, a fully automated control of parts of the process chain like degassing is possible. This technology does guarantee a pre-specifi ed and documented melt quality in each melt treatment batch. Furthermore, to ensure that castings are consistent and predictable there is a growing realization that critical parameters such as metal cleanliness must be measured prior to casting. There exists accepted methods for measuring the cleanliness of an aluminum melt but these can be both slow and costly. A simple, rapid and meaningful method of measuring and bench marking the cleanliness of an aluminum melt has been developed to offer the foundry a practical method of measuring melt cleanliness. This paper shows the structure and performance of the integrated MTS melt treatment process and documents achieved melt quality standards after degassing, cleaning, modifi cation and grain refi nement operations under real foundry conditions. It also provides an insight on a melt cleanliness measuring device “Alspek MQ” to provide foundry men better tools in meeting the increasing quality and tighter specifi cation demand from the industry.

  9. Experimental Constraints on Fluid-Rock Reactions during Incipient Serpentinization of Harzburgite

    Science.gov (United States)

    Klein, F.; Grozeva, N. G.; Seewald, J.; McCollom, T. M.; Humphris, S. E.; Moskowitz, B. M.; Berquo, T. S.; Kahl, W. A.

    2014-12-01

    The exposure of mantle peridotite to water at crustal levels leads to a cascade of interconnected dissolution-precipitation and reduction-oxidation reactions - a process referred to as serpentinization. These reactions have major implications for microbial life through the provision of hydrogen (H2). To simulate incipient serpentinization and the release of H2 under well-constrained conditions, we reacted uncrushed harzburgite with chemically modified seawater at 300°C and 35 MPa for ca. 1.5 years (13441 hours), monitored changes in fluid chemistry over time, and examined the secondary mineralogy at the termination of the experiment. Approximately 4 mol % of the protolith underwent alteration forming serpentine, accessory magnetite, chlorite, and traces of calcite and heazlewoodite. Alteration textures bear remarkable similarities to those found in partially serpentinized abyssal peridotites. Neither brucite nor talc precipitated during the experiment. Given that the starting material contained ~3.8 times more olivine than orthopyroxene on a molar basis, mass balance requires that dissolution of orthopyroxene was significantly faster than dissolution of olivine. However, the H2 release rate was not uniform, slowing from ~2 nmol H2(aq) gperidotite-1 s-1 at the beginning of the experiment to ~0.2 nmol H2(aq) gperidotite-1 s-1 at its termination. Serpentinization consumed water but did not release significant amounts of dissolved species (other than H2) suggesting that incipient hydration reactions involved a volume increase of ~40%. The reduced access of water to olivine surfaces due to filling of fractures and coating of primary minerals with alteration products led to decreased rates of serpentinization and H2 release. While this concept might seem at odds with completely serpentinized seafloor peridotites, reaction-driven fracturing offers an intriguing solution to the seemingly self-limiting nature of serpentinization. Indeed, the reacted sample revealed a

  10. White coat hypertension in NIDDM patients with and without incipient and overt diabetic nephropathy

    DEFF Research Database (Denmark)

    Nielsen, F S; Gaede, P; Vedel, P

    1997-01-01

    OBJECTIVE: Early data have suggested a high prevalence of white coat hypertension (approximately 50%) in NIDDM patients. To study this phenomenon further, we determined the prevalence of white coat hypertension in NIDDM patients with normo- or microalbuminuria or with diabetic nephropathy. RESEARCH...... DESIGN AND METHODS: Three groups of hypertensive NIDDM patients (repeated clinic blood pressure > 140/90 mmHg or antihypertensive treatment) attending the Steno Diabetes Center were investigated in a cross-sectional study. Group 1 had normoalbuminuria (a urinary albumin excretion [UAE] rate ... in normoalbuminuric NIDDM patients resembles that observed in nondiabetic subjects with essential hypertension, whereas the prevalence is significantly lower in NIDDM patients with incipient or overt diabetic nephropathy, suggesting a difference between primary and secondary hypertension....

  11. Monitoring kidney function in type 2 diabetic patients with incipient and overt diabetic nephropathy

    DEFF Research Database (Denmark)

    Rossing, Peter; Rossing, Kasper; Gaede, Peter

    2006-01-01

    -EDTA. RESEARCH DESIGN AND METHODS: We followed a cohort of 156 microalbuminuric type 2 diabetic patients for 8 years with four measurements of GFR and another cohort of 227 type 2 diabetic patients with overt diabetic nephropathy for 6.5 (range 3-17) years with seven (3-22) measurements of GFR. RESULTS...... is also significantly underestimated with both equations. This makes GFR estimations based upon these equations unacceptable for monitoring kidney function in type 2 diabetic patients with incipient and overt diabetic nephropathy.......OBJECTIVE: The purpose of this study was to assess agreement between glomerular filtration rate (GFR) and the decline in GFR estimated with the Modification of Diet in Renal Disease (MDRD) Study Group equation or the Cockcroft-Gault formula and measured by the plasma clearance of 51Cr...

  12. Incipient ferroelectricity of water molecules confined to nano-channels of beryl

    Science.gov (United States)

    Gorshunov, B. P.; Torgashev, V. I.; Zhukova, E. S.; Thomas, V. G.; Belyanchikov, M. A.; Kadlec, C.; Kadlec, F.; Savinov, M.; Ostapchuk, T.; Petzelt, J.; Prokleška, J.; Tomas, P. V.; Pestrjakov, E. V.; Fursenko, D. A.; Shakurov, G. S.; Prokhorov, A. S.; Gorelik, V. S.; Kadyrov, L. S.; Uskov, V. V.; Kremer, R. K.; Dressel, M.

    2016-09-01

    Water is characterized by large molecular electric dipole moments and strong interactions between molecules; however, hydrogen bonds screen the dipole-dipole coupling and suppress the ferroelectric order. The situation changes drastically when water is confined: in this case ordering of the molecular dipoles has been predicted, but never unambiguously detected experimentally. In the present study we place separate H2O molecules in the structural channels of a beryl single crystal so that they are located far enough to prevent hydrogen bonding, but close enough to keep the dipole-dipole interaction, resulting in incipient ferroelectricity in the water molecular subsystem. We observe a ferroelectric soft mode that causes Curie-Weiss behaviour of the static permittivity, which saturates below 10 K due to quantum fluctuations. The ferroelectricity of water molecules may play a key role in the functioning of biological systems and find applications in fuel and memory cells, light emitters and other nanoscale electronic devices.

  13. White coat hypertension in NIDDM patients with and without incipient and overt diabetic nephropathy

    DEFF Research Database (Denmark)

    Nielsen, F S; Gaede, P; Vedel, P

    1997-01-01

    in normoalbuminuric NIDDM patients resembles that observed in nondiabetic subjects with essential hypertension, whereas the prevalence is significantly lower in NIDDM patients with incipient or overt diabetic nephropathy, suggesting a difference between primary and secondary hypertension.......OBJECTIVE: Early data have suggested a high prevalence of white coat hypertension (approximately 50%) in NIDDM patients. To study this phenomenon further, we determined the prevalence of white coat hypertension in NIDDM patients with normo- or microalbuminuria or with diabetic nephropathy. RESEARCH...... DESIGN AND METHODS: Three groups of hypertensive NIDDM patients (repeated clinic blood pressure > 140/90 mmHg or antihypertensive treatment) attending the Steno Diabetes Center were investigated in a cross-sectional study. Group 1 had normoalbuminuria (a urinary albumin excretion [UAE] rate

  14. Radiographic diagnosis of incipient proximal caries: an ex-vivo study.

    Science.gov (United States)

    da Silva Neto, José Moreira; dos Santos, Rosenês Lima; Sampaio, Maria Carmeli Correia; Sampaio, Fábio Correia; Passos, Isabela Albuquerque

    2008-01-01

    The aim of this ex vivo study was to compare visual clinical and radiographic examinations to the histological analysis for proximal caries diagnosis in extracted permanent molars and premolars. The relationship between clinical aspects and carious lesions was also evaluated. Eighty-eight proximal surfaces (44 freshly extracted teeth) were longitudinally sectioned with a 370-microm diamond disk, thinned with wet silicon carbide paper and observed with a stereomicroscope at x40 magnification. Sensitivity and specificity were 65.6% and 83.3% for clinical examination and 29.7% and 95.8% for radiographic examination, respectively. Kappa values ranged from 0.64 to 0.91. The white spots corresponded to lesions restricted to enamel, while the dark spots corresponded to lesions that reached the dentinoenamel junction. In most cases, cavitation corresponded to dentin lesions. It may be concluded that interproximal radiographic examination is not a reliable method for detection of incipient proximal carious lesions.

  15. Incipient Social Groups: An Analysis via In-Vivo Behavioral Tracking.

    Directory of Open Access Journals (Sweden)

    Jamin Halberstadt

    Full Text Available Social psychology is fundamentally the study of individuals in groups, yet there remain basic unanswered questions about group formation, structure, and change. We argue that the problem is methodological. Until recently, there was no way to track who was interacting with whom with anything approximating valid resolution and scale. In the current study we describe a new method that applies recent advances in image-based tracking to study incipient group formation and evolution with experimental precision and control. In this method, which we term "in vivo behavioral tracking," we track individuals' movements with a high definition video camera mounted atop a large field laboratory. We report results of an initial study that quantifies the composition, structure, and size of the incipient groups. We also apply in-vivo spatial tracking to study participants' tendency to cooperate as a function of their embeddedness in those crowds. We find that participants form groups of seven on average, are more likely to approach others of similar attractiveness and (to a lesser extent gender, and that participants' gender and attractiveness are both associated with their proximity to the spatial center of groups (such that women and attractive individuals are more likely than men and unattractive individuals to end up in the center of their groups. Furthermore, participants' proximity to others early in the study predicted the effort they exerted in a subsequent cooperative task, suggesting that submergence in a crowd may predict social loafing. We conclude that in vivo behavioral tracking is a uniquely powerful new tool for answering longstanding, fundamental questions about group dynamics.

  16. Incipient Social Groups: An Analysis via In-Vivo Behavioral Tracking.

    Science.gov (United States)

    Halberstadt, Jamin; Jackson, Joshua Conrad; Bilkey, David; Jong, Jonathan; Whitehouse, Harvey; McNaughton, Craig; Zollmann, Stefanie

    2016-01-01

    Social psychology is fundamentally the study of individuals in groups, yet there remain basic unanswered questions about group formation, structure, and change. We argue that the problem is methodological. Until recently, there was no way to track who was interacting with whom with anything approximating valid resolution and scale. In the current study we describe a new method that applies recent advances in image-based tracking to study incipient group formation and evolution with experimental precision and control. In this method, which we term "in vivo behavioral tracking," we track individuals' movements with a high definition video camera mounted atop a large field laboratory. We report results of an initial study that quantifies the composition, structure, and size of the incipient groups. We also apply in-vivo spatial tracking to study participants' tendency to cooperate as a function of their embeddedness in those crowds. We find that participants form groups of seven on average, are more likely to approach others of similar attractiveness and (to a lesser extent) gender, and that participants' gender and attractiveness are both associated with their proximity to the spatial center of groups (such that women and attractive individuals are more likely than men and unattractive individuals to end up in the center of their groups). Furthermore, participants' proximity to others early in the study predicted the effort they exerted in a subsequent cooperative task, suggesting that submergence in a crowd may predict social loafing. We conclude that in vivo behavioral tracking is a uniquely powerful new tool for answering longstanding, fundamental questions about group dynamics.

  17. Plucking in Mixed Alluvial-Bedrock Rivers: The Incipient Motion Problem

    Science.gov (United States)

    Hurst, A. A.; Furbish, D. J.

    2015-12-01

    Bedrock river channel erosion is an important factor in the evolution of landscapes, driving the relief of mountainous drainage basins and setting the lowest erosional positions of terrestrial landscapes. The mechanics behind erosional processes (predominantly plucking and abrasion) in these rivers are only recently being explored in depth. Plucking, the fracture and extraction of jointed blocks, is observationally an order of magnitude more efficient than abrasion, but if a river cannot provide the force necessary to move the plucked block, erosion by plucking cannot proceed. Therefore, incipient motion of blocks starting at rest on a solid surface is an important factor in erosion by plucking. Calculations of forces necessary for incipient motion require values of drag coefficients, which do not exist for bedrock contact geometry. We discovered from experiments on a flume that drag coefficients (CD) are inversely proportional to aspect ratios (RA), defined as the frontal block height to width. We used the relationship with field data from plucked blocks at a stream at Montgomery Bell State Park in Burns, TN, a mixed-alluvial bedrock channel with an actively incising knick zone, to support our theory and experimental data. Sizes of plucked blocks were compared to the velocities needed to move them, and then calculations done for bankfull velocities at the stream at Montgomery Bell to determine if it could attain these velocities. It was discovered that this stream has a bankfull depth-averaged velocity of 1.26 m s-1 and is capable of moving a large range of plucked block sizes. Therefore, erosion of this particular stream is plucking-limited, not transport-limited.

  18. Improved detection of incipient anomalies via multivariate memory monitoring charts: Application to an air flow heating system

    KAUST Repository

    Harrou, Fouzi

    2016-08-11

    Detecting anomalies is important for reliable operation of several engineering systems. Multivariate statistical monitoring charts are an efficient tool for checking the quality of a process by identifying abnormalities. Principal component analysis (PCA) was shown effective in monitoring processes with highly correlated data. Traditional PCA-based methods, nevertheless, often are relatively inefficient at detecting incipient anomalies. Here, we propose a statistical approach that exploits the advantages of PCA and those of multivariate memory monitoring schemes, like the multivariate cumulative sum (MCUSUM) and multivariate exponentially weighted moving average (MEWMA) monitoring schemes to better detect incipient anomalies. Memory monitoring charts are sensitive to incipient anomalies in process mean, which significantly improve the performance of PCA method and enlarge its profitability, and to utilize these improvements in various applications. The performance of PCA-based MEWMA and MCUSUM control techniques are demonstrated and compared with traditional PCA-based monitoring methods. Using practical data gathered from a heating air-flow system, we demonstrate the greater sensitivity and efficiency of the developed method over the traditional PCA-based methods. Results indicate that the proposed techniques have potential for detecting incipient anomalies in multivariate data. © 2016 Elsevier Ltd

  19. Incipient-signature identification of mechanical anomalies in a ship-borne satellite antenna system using an ensemble multiwavelet

    International Nuclear Information System (INIS)

    He, Shuilong; Zi, Yanyang; Chen, Jinglong; Chen, Binqiang; He, Zhengjia; Zhao, Chenlu; Yuan, Jing

    2014-01-01

    The instrumented tracking and telemetry ship with a ship-borne satellite antenna (SSA) is the critical device to ensure high quality of space exploration work. To effectively detect mechanical anomalies that can lead to unexpected downtime of the SSA, an ensemble multiwavelet (EM) is presented for identifying the anomaly related incipient-signatures within the measured dynamic signals. Rather than using a predetermined basis as in a conventional multiwavelet, an EM optimizes the matching basis which satisfactorily adapts to the anomaly related incipient-signatures. The construction technique of an EM is based on the conjunction of a two-scale similarity transform (TST) and lifting scheme (LS). For the technique above, the TST improves the regularity by increasing the approximation order of multiscaling functions, while subsequently the LS enhances the smoothness and localizability via utilizing the vanishing moment of multiwavelet functions. Moreover, combining the Hilbert transform with EM decomposition, we identify the incipient-signatures induced by the mechanical anomalies from the measured dynamic signals. A numerical simulation and two successful applications of diagnosis cases (a planetary gearbox and a roller bearing) demonstrate that the proposed technique is capable of dealing with the challenging incipient-signature identification task even though spectral complexity, as well as the strong amplitude/frequency modulation effect, is present in the dynamic signals. (paper)

  20. Elastic properties of silicate melts

    DEFF Research Database (Denmark)

    Clark, Alisha N.; Lesher, Charles E.

    2017-01-01

    Low seismic velocity regions in the mantle and crust are commonly attributed to the presence of silicate melts. Determining melt volume and geometric distribution is fundamental to understanding planetary dynamics. We present a new model for seismic velocity reductions that accounts for the anoma......Low seismic velocity regions in the mantle and crust are commonly attributed to the presence of silicate melts. Determining melt volume and geometric distribution is fundamental to understanding planetary dynamics. We present a new model for seismic velocity reductions that accounts...... for the anomalous compressibility of silicate melt, rendering compressional wave velocities more sensitive to melt fraction and distribution than previous estimates. Forward modeling predicts comparable velocity reductions for compressional and shear waves for partially molten mantle, and for low velocity regions...

  1. Application of the Cold Crucible for Melting of UO2/ZrO2 Mixtures

    International Nuclear Information System (INIS)

    Hong, S.W.; Min, B.T.; Shin, Y.S.; Park, I.K.; Kim, J.H.; Song, J.H.; Kim, H.D.

    2002-01-01

    The melting and discharge technique of UO 2 /ZrO 2 mixtures using the cold crucible melting method that does not need a separate crucible such as tungsten one with high melting point is developed and applied to the KAERI FCI test called TROI. To discharge the melt from a cold crucible into a fuel-coolant interaction chamber after melting, a plug is specially designed using the concept for electro-magnetic field characteristics so as to as thin as possible the crust that is formed between the melt and plug. Its function keeps the melt in the crucible during melting period and provides the melt discharge path. About 8.5 kg melt is discharged from the cold crucible to the melt-water interaction chamber through the punched hole with 8 cm in diameter. The melt temperature is also measured and analyzed from observation of the melt surface. The power balance using the operating parameters such as current, voltage and coupling factor of R.F generator is analyzed. (authors)

  2. Logistics Reduction: Heat Melt Compactor

    Data.gov (United States)

    National Aeronautics and Space Administration — The Advanced Exploration Systems (AES) Logistics Reduction (LR) project Heat Melt Compactor (HMC) technology is a waste management technology. Currently, there are...

  3. Melting of contaminated metallic waste

    International Nuclear Information System (INIS)

    Lee, Y.-S.; Cheng, S.-Y.; Kung, H.-T.; Lin, L.-F.

    2004-01-01

    Approximately 100 tons of contaminated metallic wastes were produced each year due to maintenance for each TPC's nuclear power reactor and it was roughly estimated that there will be 10,000 tons of metallic scraps resulted from decommissioning of each reactor in the future. One means of handling the contaminated metal is to melt it. Melting process owns not only volume reduction which saves the high cost of final disposal but also resource conservation and recycling benefits. Melting contaminated copper and aluminum scraps in the laboratory scale have been conducted at INER. A total of 546 kg copper condenser tubes with a specific activity of about 2.7 Bq/g was melted in a vacuum induction melting facility. Three types of products, ingot, slag and dust were derived from the melting process, with average activities of 0.10 Bq/g, 2.33 Bq/g and 84.3 Bq/g respectively. After the laboratory melting stage, a pilot plant with a 500 kg induction furnace is being designed to melt the increasingly produced contaminated metallic scraps from nuclear facilities and to investigate the behavior of different radionuclides during melting. (author)

  4. Glass forming ability of calcium aluminosilicate melts

    DEFF Research Database (Denmark)

    Moesgaard, Mette; Yue, Yuanzheng

    2011-01-01

    The glass forming ability (GFA) of two series of calcium aluminosilicate melts is studied by measuring their viscous behavior and crystallization tendency. The first series consists of five compositions on the joining line between the eutectic point of anorthite-wollastonite-tridymite and that of......The glass forming ability (GFA) of two series of calcium aluminosilicate melts is studied by measuring their viscous behavior and crystallization tendency. The first series consists of five compositions on the joining line between the eutectic point of anorthite......-wollastonite-tridymite and that of anorthite-wollastonite-gehlenite. The series includes the eutectic compositions as end members. The second series consists of five compositions on a line parallel to the joining line on the alumina rich side. In the present work, GFA is described in terms of glass stability, i.e., the ability of a glass...... to resist crystallization during reheating. In addition, the fragility index (m) is derived by fitting the viscosity data with the Avramov-Milchev equation. The results show that m is inversely proportional to the glass stability for the two series of melts, implying that m is an indirect measure of GFA...

  5. A thermo dynamical model for the shape and size effect on melting of boron carbide nanoparticles.

    Science.gov (United States)

    Antoniammal, Paneerselvam; Arivuoli, Dakshanamoorthy

    2012-02-01

    The size and shape dependence of the melting temperature of Boron Carbide (B4C) nanoparticles has been investigated with a numerical thermo dynamical approach. The problem considered in this paper is the inward melting of nanoparticles with spherical and cylindrical geometry. The cylindrical Boron Carbide (B4C) nanoparticles, whose melting point has been reported to decrease with decreasing particle radius, become larger than spherical shaped nanoparticle. Comparative investigation of the size dependence of the melting temperature with respect to the two shapes is also been done. The melting temperature obtained in the present study is approximately a dealing function of radius, in a good agreement with prediction of thermo dynamical model.

  6. Free dendritic growth in viscous melts - Cyclohexanol

    Science.gov (United States)

    Singh, N. B.; Glicksman, M. E.

    1989-01-01

    Experiments were carried out to measure the growth speed, V, and dendritic tip radius, R, of highly purified cyclohexanol. The data show that VR-squared = constant over the entire experimentally observed supercooling range, Delta T is between 0.1 and 1 K. The stability parameter estimated from this result indicates that sigma(asterisk) = 0.027, a value in good agreement with the values of sigma(asterisk) found for the cubic plastic crystals succinonitrile pivalic acid. Cyclohexanol differs from other carefully measured plastic crystals in that the viscosity of its melt at the melting point is about 20 times higher, so gravity-induced convection remains weak even at small supercoolings.

  7. Nanorheology of Entangled Polymer Melts

    Science.gov (United States)

    Ge, Ting; Grest, Gary S.; Rubinstein, Michael

    2018-02-01

    We use molecular simulations to probe the local viscoelasticity of an entangled polymer melt by tracking the motion of embedded nonsticky nanoparticles (NPs). As in conventional microrheology, the generalized Stokes-Einstein relation is employed to extract an effective stress relaxation function GGSE(t ) from the mean square displacement of NPs. GGSE(t ) for different NP diameters d are compared with the stress relaxation function G (t ) of a pure polymer melt. The deviation of GGSE(t ) from G (t ) reflects the incomplete coupling between NPs and the dynamic modes of the melt. For linear polymers, a plateau in GGSE(t ) emerges as d exceeds the entanglement mesh size a and approaches the entanglement plateau in G (t ) for a pure melt with increasing d . For ring polymers, as d increases towards the spanning size R of ring polymers, GGSE(t ) approaches G (t ) of the ring melt with no entanglement plateau.

  8. Experiments on melt droplets falling into a water pool

    Energy Technology Data Exchange (ETDEWEB)

    Okkonen, T.; Sehgal, B.R. [Royal Inst. of Tech., Stockholm (Sweden). Div. of Nuclear Power Safety

    1998-01-01

    This paper presents experimental data and analysis related to melt droplets falling into a water pool. A binary CaO-B{sub 2}O{sub 3} melt mixture is used to study the influence of melt superheat and water subcooling on droplet deformation and fragmentation. For the conditions studied (We {<=} 1000), the surface tension of the melt droplet and the film boiling stability greatly affect the fragmentation behaviour. If the melt temperature is between the liquidus and solidus point (mushy zone) or if the film boiling is stable due to a relatively low subcooling, the droplet deformation and fragmentation are mitigated. This behaviour can be related to the effective Weber number (We) of the melt droplet upon entry into the water pool. Similar phenomena can be expected also for interactions of corium (UO{sub 2}-ZrO{sub 2}) and water, which are characterized by a potentially fast transformation of melt into the mushy zone and by particularly stable film boiling. (author)

  9. Hot-melt extrusion--basic principles and pharmaceutical applications.

    Science.gov (United States)

    Lang, Bo; McGinity, James W; Williams, Robert O

    2014-09-01

    Originally adapted from the plastics industry, the use of hot-melt extrusion has gained favor in drug delivery applications both in academia and the pharmaceutical industry. Several commercial products made by hot-melt extrusion have been approved by the FDA, demonstrating its commercial feasibility for pharmaceutical processing. A significant number of research articles have reported on advances made regarding the pharmaceutical applications of the hot-melt extrusion processing; however, only limited articles have been focused on general principles regarding formulation and process development. This review provides an in-depth analysis and discussion of the formulation and processing aspects of hot-melt extrusion. The impact of physicochemical properties of drug substances and excipients on formulation development using a hot-melt extrusion process is discussed from a material science point of view. Hot-melt extrusion process development, scale-up, and the interplay of formulation and process attributes are also discussed. Finally, recent applications of hot-melt extrusion to a variety of dosage forms and drug substances have also been addressed.

  10. A metastable liquid melted from a crystalline solid under decompression

    Science.gov (United States)

    Lin, Chuanlong; Smith, Jesse S.; Sinogeikin, Stanislav V.; Kono, Yoshio; Park, Changyong; Kenney-Benson, Curtis; Shen, Guoyin

    2017-01-01

    A metastable liquid may exist under supercooling, sustaining the liquid below the melting point such as supercooled water and silicon. It may also exist as a transient state in solid-solid transitions, as demonstrated in recent studies of colloidal particles and glass-forming metallic systems. One important question is whether a crystalline solid may directly melt into a sustainable metastable liquid. By thermal heating, a crystalline solid will always melt into a liquid above the melting point. Here we report that a high-pressure crystalline phase of bismuth can melt into a metastable liquid below the melting line through a decompression process. The decompression-induced metastable liquid can be maintained for hours in static conditions, and transform to crystalline phases when external perturbations, such as heating and cooling, are applied. It occurs in the pressure-temperature region similar to where the supercooled liquid Bi is observed. Akin to supercooled liquid, the pressure-induced metastable liquid may be more ubiquitous than we thought.

  11. Can Monitoring Fetal Intestinal Inflammation Using Heart Rate Variability Analysis Signal Incipient Necrotizing Enterocolitis of the Neonate?

    Science.gov (United States)

    Liu, Hai Lun; Garzoni, Luca; Herry, Christophe; Durosier, Lucien Daniel; Cao, Mingju; Burns, Patrick; Fecteau, Gilles; Desrochers, André; Patey, Natalie; Seely, Andrew J E; Faure, Christophe; Frasch, Martin G

    2016-04-01

    Necrotizing enterocolitis of the neonate is an acute inflammatory intestinal disease that can cause necrosis and sepsis. Chorioamnionitis is a risk factor of necrotizing enterocolitis. The gut represents the biggest vagus-innervated organ. Vagal activity can be measured via fetal heart rate variability. We hypothesized that fetal heart rate variability can detect fetuses with incipient gut inflammation. Prospective animal study. University research laboratory. Chronically instrumented near-term fetal sheep (n = 21). Animals were surgically instrumented with vascular catheters and electrocardiogram to allow manipulation and recording from nonanesthetized animals. In 14 fetal sheep, inflammation was induced with lipopolysaccharide (IV) to mimic chorioamnionitis. Fetal arterial blood samples were drawn at selected time points over 54 hours post lipopolysaccharide for blood gas and cytokines (interleukin-6 and tumor necrosis factor-α enzymelinked immunosorbent assay). Fetal heart rateV was quantified throughout the experiment. The time-matched fetal heart rate variability measures were correlated to the levels of interleukin-6 and tumor necrosis factor-α. Upon necropsy, ionized calcium binding adaptor molecule 1+ (Iba1+), CD11c+ (M1), CD206+ (M2 macrophages), and occludin (leakiness marker) immunofluorescence in the terminal ileum was quantified along with regional Iba1+ signal in the brain (microglia). Interleukin-6 peaked at 3 hours post lipopolysaccharide accompanied by mild cardiovascular signs of sepsis. At 54 hours, we identified an increase in Iba1+ and, specifically, M1 macrophages in the ileum accompanied by increased leakiness, with no change in Iba1 signal in the brain. Preceding this change on tissue level, at 24 hours, a subset of nine fetal heart rate variability measures correlated exclusively to the Iba+ markers of ileal, but not brain, inflammation. An additional fetal heart rate variability measure, mean of the differences of R-R intervals

  12. Incipient mantle plume evolution: Constraints from ancient landscapes buried beneath the North Sea

    Science.gov (United States)

    Stucky de Quay, G.; Roberts, G. G.; Watson, J. S.; Jackson, C. A.-L.

    2017-03-01

    Geological observations that constrain the history of mantle convection are sparse despite its importance in determining vertical and horizontal plate motions, plate rheology, and magmatism. We use a suite of geological and geophysical observations from the northern North Sea to constrain evolution of the incipient Paleocene-Eocene Icelandic plume. Well data and a three-dimensional seismic survey are used to reconstruct a 58-55 Ma landscape now buried ˜1.5 km beneath the seabed in the Bressay region. Geochemical analyses of cuttings from wells that intersect the landscape indicate the presence of angiosperm debris. These observations, combined with presence of coarse clastic material, interpreted beach ridges, and a large dendritic drainage network, indicate that this landscape formed subaerially. Longitudinal profiles of paleo-rivers were extracted and inverted for an uplift rate history, indicating three distinct phases of uplift and total cumulative uplift of ˜350 m. Dinoflagellate cysts in the surrounding marine stratigraphy indicate that this terrestrial landscape formed in ˜150 km/Ma.

  13. Incipient microphase separation in short chain perfluoropolyether-block-poly(ethylene oxide) copolymers.

    Science.gov (United States)

    Chintapalli, Mahati; Timachova, Ksenia; Olson, Kevin R; Banaszak, Michał; Thelen, Jacob L; Mecham, Sue J; DeSimone, Joseph M; Balsara, Nitash P

    2017-06-07

    Incipient microphase separation is observed by wide angle X-ray scattering (WAXS) in short chain multiblock copolymers consisting of perfluoropolyether (PFPE) and poly(ethylene oxide) (PEO) segments. Two PFPE-PEO block copolymers were studied; one with dihydroxyl end groups and one with dimethyl carbonate end groups. Despite having a low degree of polymerization (N ∼ 10), these materials exhibited significant scattering intensity, due to disordered concentration fluctuations between their PFPE-rich and PEO-rich domains. The disordered scattering intensity was fit to a model based on a multicomponent random phase approximation to determine the value of the interaction parameter, χ, and the radius of gyration, R g . Over the temperature range 30-90 °C, the values of χ were determined to be very large (∼2-2.5), indicating a high degree of immiscibility between the PFPE and PEO blocks. In PFPE-PEO, due to the large electron density contrast between the fluorinated and non-fluorinated block and the high value of χ, disordered scattering was detected at intermediate scattering angles, (q ∼ 2 nm -1 ) for relatively small polymer chains. Our ability to detect concentration fluctuations was enabled by both a relatively large value of χ and significant scattering contrast.

  14. Transcriptome analysis of synaptoneurosomes identifies neuroplasticity genes overexpressed in incipient Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Celia Williams

    Full Text Available In Alzheimer's disease (AD, early deficits in learning and memory are a consequence of synaptic modification induced by toxic beta-amyloid oligomers (oAbeta. To identify immediate molecular targets downstream of oAbeta binding, we prepared synaptoneurosomes from prefrontal cortex of control and incipient AD (IAD patients, and isolated mRNAs for comparison of gene expression. This novel approach concentrates synaptic mRNA, thereby increasing the ratio of synaptic to somal mRNA and allowing discrimination of expression changes in synaptically localized genes. In IAD patients, global measures of cognition declined with increasing levels of dimeric Abeta (dAbeta. These patients also showed increased expression of neuroplasticity related genes, many encoding 3'UTR consensus sequences that regulate translation in the synapse. An increase in mRNA encoding the GluR2 subunit of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR was paralleled by elevated expression of the corresponding protein in IAD. These results imply a functional impact on synaptic transmission as GluR2, if inserted, maintains the receptors in a low conductance state. Some overexpressed genes may induce early deficits in cognition and others compensatory mechanisms, providing targets for intervention to moderate the response to dAbeta.

  15. Evidence of incipient speciation in Astyanax scabripinnis species complex (Teleostei: Characidae

    Directory of Open Access Journals (Sweden)

    Jonathan P. Castro

    Full Text Available Two populations of the Astyanax scabripinniscomplex, isolated by a waterfall with over 100 meters depth and inhabiting different altitudes of the same river (1850 m a.s.l. and 662 m a.s.l. were compared in reproductive data, geometric morphometry, tooth morphology, anal-fin rays counts, and karyotype, in order to test the hypothesis of speciation between the two populations. The results in the geometric morphometry analysis showed differences between the populations. Discriminant function analysis (DFA and canonical variance analysis revealed sexual dimorphism. Secondary sexual characters, such as hooks in the anal fin rays of the males are absent in the lower altitude population. Both populations had the same macro karyotype structure, except for the absence of B chromosomes in the lower altitude population. The fluorescence in situ hybridization showed differences for both markers (18S rDNA and 5S rDNA, and reproductive data suggests pre-zygotic reproductive isolation among the two populations. The data showed the absence of gene flow, indicating that an incipient speciation process has occurred, which leads the two populations to follow independent evolutionary pathways.

  16. Threshold Criteria for Incipient Grain Motion with Turbulent Fluctuations on a Horizontal Bed

    International Nuclear Information System (INIS)

    Wan, M.W.H.M.

    2015-01-01

    The effect of turbulent fluctuations on the threshold criteria for incipient grain motion over a wide range of sediment size is investigated. In this work, attention is paid to the comparison of the critical Shields parameter θ c profile obtained when the near-bed fluid forces induced sediment motion are oscillating-grid turbulence and a single idealised eddy of vortex ring. For experimental work, near-spherical monodisperse sediments were used throughout with relative densities of 1.2 and 2.5 and mean diameters d ranging between 80 and 1087 μm. The measured values of θ c on a horizontal bed α = 0 (hence denoted as θ c0 ), were compared to the θ c0 profiles obtained by grid turbulence and vortex ring experiments. Although different in magnitude, the θ c0 profiles were comparable, that is the θ c0 were seen to increase monotonically for hydraulically smooth bed forms and to be approximately constant for hydraulically rough bed forms. However the limit of hydraulically smooth region was found to vary between the oscillating-grid turbulence experiments, where wider smooth region was found when the turbulent fluctuations used to calculate θ c0 is not the near-bed velocity. (author)

  17. Advanced power system protection and incipient fault detection and protection of spaceborne power systems

    Science.gov (United States)

    Russell, B. Don

    1989-01-01

    This research concentrated on the application of advanced signal processing, expert system, and digital technologies for the detection and control of low grade, incipient faults on spaceborne power systems. The researchers have considerable experience in the application of advanced digital technologies and the protection of terrestrial power systems. This experience was used in the current contracts to develop new approaches for protecting the electrical distribution system in spaceborne applications. The project was divided into three distinct areas: (1) investigate the applicability of fault detection algorithms developed for terrestrial power systems to the detection of faults in spaceborne systems; (2) investigate the digital hardware and architectures required to monitor and control spaceborne power systems with full capability to implement new detection and diagnostic algorithms; and (3) develop a real-time expert operating system for implementing diagnostic and protection algorithms. Significant progress has been made in each of the above areas. Several terrestrial fault detection algorithms were modified to better adapt to spaceborne power system environments. Several digital architectures were developed and evaluated in light of the fault detection algorithms.

  18. On the Shape of the Crest of Short Wavelength Water Waves at Incipient Breaking

    Science.gov (United States)

    Diorio, J. D.; Liu, X.; Duncan, J. H.

    2007-11-01

    Breaking waves with wavelengths ranging from about 0.1 to 1.2 m are studied experimentally in a wind wave tank that is 11.8 m long, 1.15 m wide and 1.8 m high (1.0 m of water). The tank includes a wind tunnel with speeds up to 10 m/s and a programmable wave maker that resides at the upwind end of the tank. The shortest waves are generated by wind with speeds ranging from about 4 to 7 m/s. The longest waves are generated mechanically from focused wave packets with average frequencies ranging from 1.15 to 1.42 Hz. Waves with intermediate lengths are formed either by wind or by a nonlinear wave train with unstable sidebands generated by the wave maker. At incipient breaking, all the waves have a capillary-ripple pattern at the crest rather than a plunging jet. It is found that in spite of the wide range of wavelengths and major differences in the generation methods, the shapes of the capillary-ripple pattern are remarkably similar. Various geometrical parameters including the length of the first capillary wave and the length and thickness of the bulge that forms at the crest are extracted from the data. The variation of these parameters with gravity wavelength and slope of the front face of the wave is examined.

  19. Abnormal albuminuria and blood pressure rise in incipient diabetic nephropathy induced by exercise

    DEFF Research Database (Denmark)

    Christensen, Cramer

    1984-01-01

    The aim of the study was to evaluate the influence of light to moderate dynamic work (450 kpm/min followed by 600 kpm/min during 20 min each) on the blood pressure and renal protein handling in insulin-dependent diabetic patients with incipient nephropathy (D3) (elevated baseline albumin excretion...... but without clinical proteinuria). Fifteen male diabetic patients (D3) with a mean age of 26.5 +/- 4.8 years (SD) and a diabetes duration of 15.6 +/- 3.4 years (SD), 11 comparable diabetic patients with normal urinary albumin excretion (D2), and ten non-diabetic subjects (C) were studied. In D3 baseline....../min in D3 (193.0 mm Hg +/- 23.0) compared to D2 (170.5 +/- 17.3, 2P = 1.2%) and C (157.5 mm Hg +/- 20.9, 2P = 0.07%). Baseline albumin excretion in D3 was 82.6 micrograms/min X/ divided by 2.5 (geometric mean X/ divided by tolerance factor) and during exercise the maximal albumin excretion rose to 195...

  20. Comparison of nano-hydroxyapatite and sodium fluoride mouthrinse for remineralization of incipient carious lesions.

    Directory of Open Access Journals (Sweden)

    Roza Haghgoo

    2014-08-01

    Full Text Available Dental caries is an infectious disease that can be prevented in several ways. The aim of this study was to compare the efficacy of sodium fluoride mouthrinse and nano- hydroxyapatite (nano-HA for the remineralization of incipient caries.After obtaining different concentrations of nano-HA (0-2-5-10%, 60 sound premolars fixed in acrylic blocks were coated with nail polish except for one surface. Ten teeth (control group were stored in distilled water and the remaining 50 samples were demineralized by immersion in 13 ml of 0.1 M lactic acid and 0.2% poly acrylic acid for 48 hours. Their microhardness was then measured and compared to that of the control group. Next, the 50 test teeth were randomly divided into 5 groups of group1 (negative, group 2 (2% nano-HA, group 3 (5% nano-HA, group 4(10% nano-HA and group 5 (0.2 NAF mouthrinse. The microhardness of the teeth was measured after 12 hours of immersion in the above-mentioned solutions. Data were analyzed using repeated measures analysis of variance (ANOVA.Microhardness of all samples decreased significantly after immersion in the demineralization solution and increased following immersion in nano-HA and NAF mouthrinses; however, this increase was not statistically significant (P=0.711.Nano-HA and NAF mouthrinses can greatly enhance remineralization and increase tooth microhardness.

  1. Incipient Fault Detection and Isolation of Field Devices in Nuclear Power Systems Using Principal Component Analysis

    International Nuclear Information System (INIS)

    Kaistha, Nitin; Upadhyaya, Belle R.

    2001-01-01

    An integrated method for the detection and isolation of incipient faults in common field devices, such as sensors and actuators, using plant operational data is presented. The approach is based on the premise that data for normal operation lie on a surface and abnormal situations lead to deviations from the surface in a particular way. Statistically significant deviations from the surface result in the detection of faults, and the characteristic directions of deviations are used for isolation of one or more faults from the set of typical faults. Principal component analysis (PCA), a multivariate data-driven technique, is used to capture the relationships in the data and fit a hyperplane to the data. The fault direction for each of the scenarios is obtained using the singular value decomposition on the state and control function prediction errors, and fault isolation is then accomplished from projections on the fault directions. This approach is demonstrated for a simulated pressurized water reactor steam generator system and for a laboratory process control system under single device fault conditions. Enhanced fault isolation capability is also illustrated by incorporating realistic nonlinear terms in the PCA data matrix

  2. Physical properties of Al-R melts

    International Nuclear Information System (INIS)

    Sidorov, V.; Gornov, O.; Bykov, V.; Son, L.; Ryltsev, R.; Uporov, S.; Shevchenko, V.; Kononenko, V.; Shunyaev, K.; Ilynykh, N.; Moiseev, G.; Kulikova, T.; Sordelet, D.

    2007-01-01

    In this work, we present experimental data of physical properties (viscosity, surface tension, magnetic susceptibility and electroresistivity) studies for Al-R (R = Ce, Pr, Sm, Gd, Dy, Ho, Yb and Y) alloys and first intermetallic compounds from aluminum side, Al 11 R 3 (Al 3 R). All properties were measured during heating up to 2000 K and the following cooling down under helium atmosphere. The main results are: (1) the electronic characteristics of the objects are in good correlation with R positions in the periodic table, but rather lower than for pure elements. The conclusion is that through all investigated temperature range, the rare-earth elements have partly covalent but not only metallic states; (2) all the melts remain strongly microheterogeneous even at high overheatings above liquidus. The existence of associations with Al 2 R type is highly probable here. Some destruction of these associations takes place with increasing temperature above melting point at the composition of Al 2 R compound. However, the transformation into true solution state is somewhere above 1900 K. To check the idea, the thermodynamic modeling of the melts was performed. It was shown that associates with Al 2 R type are stable up to 2000 K

  3. Nitrogen Control in VIM Melts

    Science.gov (United States)

    Jablonski, P. D.; Hawk, J. A.

    NETL has developed a design and control philosophy for the addition of nitrogen to austenitic and ferritic steels. The design approach uses CALPHAD as the centerpiece to predict the level to which nitrogen is soluble in both the melt and the solid. Applications of this technique have revealed regions of "exclusion" in which the alloy, while within specification limits of prescribed, cannot be made by conventional melt processing. Furthermore, other investigations have found that substantial retrograde solubility of nitrogen exists, which can become problematic during subsequent melt processing and/or other finishing operations such as welding. Additionally, the CALPHAD method has been used to adjust primary melt conditions. To that end, nitrogen additions have been made using chrome nitride, silicon nitride, high-nitrogen ferrochrome as well as nitrogen gas. The advantages and disadvantages of each approach will be discussed and NETL experience in this area will be summarized with respect to steel structure.

  4. [Pelletization of melts and liquids].

    Science.gov (United States)

    Rabisková, Miloslava

    2011-04-01

    During the second half of the last century, pelletization methods based on wetting were developed, e.g. agglomeration in coating pans, pelletization plates or fluid-bed equipment, layering of the drug in solution or suspension on inactive spherical cores, extrusion/spheronization and later on also rotoagglomeration in rotogranulators or rotoprocessors. These technologies have become a requisite part of industrial production of solid dosage forms. At present, numerous experimental papers deal with pellet preparation from melts and liquids. These new pelletization methods are the topic of the present article. Pellet preparation from melts is represented by three methods, i.e. fluid hot melt agglomeration, hot melt extrusion, and freeze pelletization. Jet cutting and cryopelletization are the techniques dealing with pellet preparation from liquids.

  5. Scaleable Clean Aluminum Melting Systems

    Energy Technology Data Exchange (ETDEWEB)

    Han, Q.; Das, S.K. (Secat, Inc.)

    2008-02-15

    The project entitled 'Scaleable Clean Aluminum Melting Systems' was a Cooperative Research and Development Agreements (CRADAs) between Oak Ridge National Laboratory (ORNL) and Secat Inc. The three-year project was initially funded for the first year and was then canceled due to funding cuts at the DOE headquarters. The limited funds allowed the research team to visit industrial sites and investigate the status of using immersion heaters for aluminum melting applications. Primary concepts were proposed on the design of furnaces using immersion heaters for melting. The proposed project can continue if the funding agency resumes the funds to this research. The objective of this project was to develop and demonstrate integrated, retrofitable technologies for clean melting systems for aluminum in both the Metal Casting and integrated aluminum processing industries. The scope focused on immersion heating coupled with metal circulation systems that provide significant opportunity for energy savings as well as reduction of melt loss in the form of dross. The project aimed at the development and integration of technologies that would enable significant reduction in the energy consumption and environmental impacts of melting aluminum through substitution of immersion heating for the conventional radiant burner methods used in reverberatory furnaces. Specifically, the program would couple heater improvements with furnace modeling that would enable cost-effective retrofits to a range of existing furnace sizes, reducing the economic barrier to application.

  6. Stress intensity factor at the tip of cladding incipient crack in RIA-simulating experiments for high-burnup PWR fuels

    International Nuclear Information System (INIS)

    Udagawa, Yutaka; Suzuki, Motoe; Sugiyama, Tomoyuki; Fuketa, Toyoshi

    2009-01-01

    RIA-simulating experiments for high-burnup PWR fuels have been performed in the NSRR, and the stress intensity factor K 1 at the tip of cladding incipient crack has been evaluated in order to investigate its validity as a PCMI failure threshold under RIA conditions. An incipient crack depth was determined by observation of metallographs. The maximum hydride-rim thickness in the cladding of the test fuel rod was regarded as the incipient crack depth in each test case. Hoop stress in the cladding periphery during the pulse power transient was calculated by the RANNS code. K 1 was calculated based on crack depth and hoop stress. According to the RANNS calculation, PCMI failure cases can be divided into two groups: failure in the elastic phase and failure in the plastic phase. In the former case, elastic deformation was predominant around the incipient crack at failure time. K 1 is available only in this case. In the latter, plastic deformation was predominant around the incipient crack at failure time. Failure in the elastic phase never occurred when K 1 was less than 17 MPa m 1/2 . For failure in the plastic phase, the plastic hoop strain of the cladding periphery at failure time clearly showed a tendency to decrease with incipient crack depth. The combination of K 1 , for failure in the elastic phase, and plastic hoop strain at failure, for failure in the plastic phase, can be an effective index of PCMI failure under RIA conditions. (author)

  7. Kullback-Leibler distance-based enhanced detection of incipient anomalies

    KAUST Repository

    Harrou, Fouzi

    2016-09-09

    Accurate and effective anomaly detection and diagnosis of modern engineering systems by monitoring processes ensure reliability and safety of a product while maintaining desired quality. In this paper, an innovative method based on Kullback-Leibler divergence for detecting incipient anomalies in highly correlated multivariate data is presented. We use a partial least square (PLS) method as a modeling framework and a symmetrized Kullback-Leibler distance (KLD) as an anomaly indicator, where it is used to quantify the dissimilarity between current PLS-based residual and reference probability distributions obtained using fault-free data. Furthermore, this paper reports the development of two monitoring charts based on the KLD. The first approach is a KLD-Shewhart chart, where the Shewhart monitoring chart with a three sigma rule is used to monitor the KLD of the response variables residuals from the PLS model. The second approach integrates the KLD statistic into the exponentially weighted moving average monitoring chart. The performance of the PLS-based KLD anomaly-detection methods is illustrated and compared to that of conventional PLS-based anomaly detection methods. Using synthetic data and simulated distillation column data, we demonstrate the greater sensitivity and effectiveness of the developed method over the conventional PLS-based methods, especially when data are highly correlated and small anomalies are of interest. Results indicate that the proposed chart is a very promising KLD-based method because KLD-based charts are, in practice, designed to detect small shifts in process parameters. © 2016 Elsevier Ltd

  8. Incipiently drowned platform deposit in cyclic Ordovician shelf sequence: Lower Ordovician Chepultepec Formation, Virginia

    Energy Technology Data Exchange (ETDEWEB)

    Bova, J.A.; Read, J.F.

    1983-03-01

    The Chepultepec interval, 145 to 260 m (476 to 853 ft) thick, in Virginia contains the Lower Member up to 150 m (492 ft) thick, and the Upper Member, up to 85 m (279 ft) thick, of peritidal cyclic limestone and dolomite, and a Middle Member, up to 110 m (360 ft) thick, of subtidal limestone and bioherms, passing northwestward into cyclic facies. Calculated long term subsidence rates were 4 to 5 cm/1000 yr (mature passive margin rates), shelf gradients were 6 cm/km, and average duration of cycles was 140,00 years. Peritidal cyclic sequences are upward shallowing sequences of pellet-skeletal limestone, thrombolites, rippled calcisiltites and intraclast grainstone, and laminite caps. They formed by rapid transgression with apparent submergence increments averaging approximately 2 m (6.5 ft) in Lower Member and 3.5 m (11.4 ft), Upper Member. Deposition during Middle Member time was dominated by skeletal limestone-mudstone, calcisiltite with storm generated fining-upward sequences, and burrow-mixed units that were formed near fair-weather wave base, along with thrombolite bioherms. Locally, there are upward shallowing sequences, of basal wackestone/mudstone to calcisiltite to bioherm complexes (locally with erosional scalloped tops). Following each submergence, carbonate sedimentation was able to build to sea level prior to renewed submergence. Large submergence events caused tidal flats to be shifted far to the west, and they were unable to prograde out onto the open shelf because of insufficient time before subsidence was renewed, and because the open shelf setting inhibited tidal flat deposition. The Middle Member represents an incipiently drowned sequence that developed by repeated submergence events.

  9. Interactions of C+(2PJ) with rare gas atoms: incipient chemical interactions, potentials and transport coefficients

    Science.gov (United States)

    Tuttle, William D.; Thorington, Rebecca L.; Viehland, Larry A.; Breckenridge, W. H.; Wright, Timothy G.

    2018-03-01

    Accurate interatomic potentials were calculated for the interaction of a singly charged carbon cation, C+, with a single rare gas atom, RG (RG = Ne-Xe). The RCCSD(T) method and basis sets of quadruple-ζ and quintuple-ζ quality were employed; each interaction energy was counterpoise corrected and extrapolated to the basis set limit. The lowest C+(2P) electronic term of the carbon cation was considered, and the interatomic potentials calculated for the diatomic terms that arise from these: 2Π and 2Σ+. Additionally, the interatomic potentials for the respective spin-orbit levels were calculated, and the effect on the spectroscopic parameters was examined. In doing this, anomalously large spin-orbit splittings for RG = Ar-Xe were found, and this was investigated using multi-reference configuration interaction calculations. The latter indicated a small amount of RG → C+ electron transfer and this was used to rationalize the observations. This is taken as evidence of an incipient chemical interaction, which was also examined via contour plots, Birge-Sponer plots and various population analyses across the C+-RG series (RG = He-Xe), with the latter showing unexpected results. Trends in several spectroscopic parameters were examined as a function of the increasing atomic number of the RG atom. Finally, each set of RCCSD(T) potentials was employed, including spin-orbit coupling to calculate the transport coefficients for C+ in RG, and the results were compared with the limited available data. This article is part of the theme issue `Modern theoretical chemistry'.

  10. Incipient balancing selection through adaptive loss of aquaporins in natural Saccharomyces cerevisiae populations.

    Science.gov (United States)

    Will, Jessica L; Kim, Hyun Seok; Clarke, Jessica; Painter, John C; Fay, Justin C; Gasch, Audrey P

    2010-04-01

    A major goal in evolutionary biology is to understand how adaptive evolution has influenced natural variation, but identifying loci subject to positive selection has been a challenge. Here we present the adaptive loss of a pair of paralogous genes in specific Saccharomyces cerevisiae subpopulations. We mapped natural variation in freeze-thaw tolerance to two water transporters, AQY1 and AQY2, previously implicated in freeze-thaw survival. However, whereas freeze-thaw-tolerant strains harbor functional aquaporin genes, the set of sensitive strains lost aquaporin function at least 6 independent times. Several genomic signatures at AQY1 and/or AQY2 reveal low variation surrounding these loci within strains of the same haplotype, but high variation between strain groups. This is consistent with recent adaptive loss of aquaporins in subgroups of strains, leading to incipient balancing selection. We show that, although aquaporins are critical for surviving freeze-thaw stress, loss of both genes provides a major fitness advantage on high-sugar substrates common to many strains' natural niche. Strikingly, strains with non-functional alleles have also lost the ancestral requirement for aquaporins during spore formation. Thus, the antagonistic effect of aquaporin function-providing an advantage in freeze-thaw tolerance but a fitness defect for growth in high-sugar environments-contributes to the maintenance of both functional and nonfunctional alleles in S. cerevisiae. This work also shows that gene loss through multiple missense and nonsense mutations, hallmarks of pseudogenization presumed to emerge after loss of constraint, can arise through positive selection.

  11. Interactions of C+(2 PJ ) with rare gas atoms: incipient chemical interactions, potentials and transport coefficients.

    Science.gov (United States)

    Tuttle, William D; Thorington, Rebecca L; Viehland, Larry A; Breckenridge, W H; Wright, Timothy G

    2018-03-13

    Accurate interatomic potentials were calculated for the interaction of a singly charged carbon cation, C + , with a single rare gas atom, RG (RG = Ne-Xe). The RCCSD(T) method and basis sets of quadruple-ζ and quintuple-ζ quality were employed; each interaction energy was counterpoise corrected and extrapolated to the basis set limit. The lowest C + ( 2 P ) electronic term of the carbon cation was considered, and the interatomic potentials calculated for the diatomic terms that arise from these: 2 Π and 2 Σ + Additionally, the interatomic potentials for the respective spin-orbit levels were calculated, and the effect on the spectroscopic parameters was examined. In doing this, anomalously large spin-orbit splittings for RG = Ar-Xe were found, and this was investigated using multi-reference configuration interaction calculations. The latter indicated a small amount of RG → C + electron transfer and this was used to rationalize the observations. This is taken as evidence of an incipient chemical interaction, which was also examined via contour plots, Birge-Sponer plots and various population analyses across the C + -RG series (RG = He-Xe), with the latter showing unexpected results. Trends in several spectroscopic parameters were examined as a function of the increasing atomic number of the RG atom. Finally, each set of RCCSD(T) potentials was employed, including spin-orbit coupling to calculate the transport coefficients for C + in RG, and the results were compared with the limited available data.This article is part of the theme issue 'Modern theoretical chemistry'. © 2018 The Author(s).

  12. Persistently elevated right ventricular index of myocardial performance in preterm infants with incipient bronchopulmonary dysplasia.

    Directory of Open Access Journals (Sweden)

    Christoph Czernik

    Full Text Available OBJECTIVES: Elevated pulmonary vascular resistance occurs during the first days after birth in all newborn infants and persists in infants at risk for bronchopulmonary dysplasia (BPD. It is difficult to measure in a non-invasive fashion. We assessed the usefulness of the right ventricular index of myocardial performance (RIMP to estimate pulmonary vascular resistance in very low birth weight infants. STUDY DESIGN: Prospective echocardiography on day of life (DOL 2, 7, 14, and 28 in 121 preterm infants (median [quartiles] gestational age 28 [26]-[29] weeks, birth weight 998 [743-1225] g of whom 36 developed BPD (oxygen supplementation at 36 postmenstrual weeks. RESULTS: RIMP derived by conventional pulsed Doppler technique was unrelated to heart rate or mean blood pressure. RIMP on DOL 2 was similar in infants who subsequently did (0.39 [0.33-0.55] and did not develop BPD (0.39 [0.28-0.51], p = 0.467. RIMP declined steadily in non-BPD infants but not in BPD infants (DOL 7: 0.31[0.22-0.39] vs. 0.35[0.29-0.48], p = 0.014; DOL 14: 0.23[0.17-0.30] vs. 0.35[0.25-0.43], p<0.001; DOL 28: 0.21[0.15-0.28] vs. 0.31 [0.21-0.35], p = 0.015. CONCLUSIONS: In preterm infants, a decline in RIMP after birth was not observed in those with incipient BPD. The pattern of RIMP measured in preterm infants is commensurate with that of pulmonary vascular resistance.

  13. History of the incipient Icelandic plume: Observations from ancient buried landscapes

    Science.gov (United States)

    Stucky de Quay, Gaia; Roberts, Gareth G.; Watson, Jonathan S.; Jackson, Christopher A.-L.

    2017-04-01

    Ancient buried terrestrial landscapes contain records of vertical motions which can be used to probe histories of geodynamical processes. In the North Atlantic Ocean, sedimentary basins contain excellent evidence that the continental shelf experienced staged subaerial exposure. For example, now buried landscapes were uplifted, rapidly eroded, and drowned close to the Paleocene-Eocene boundary. We use commercial wells and three-dimensional seismic data to reconstruct a 57-55 Ma landscape now buried 1.5 km beneath the seabed in the Bressay area of the northern North Sea. Geochemical analyses of organic matter from core samples intersecting the erosional landscape indicate the presence of angiosperm (flowering plant) debris. Combined with the presence of coarse clastic material, mapped beach ridges, and dendritic drainage patterns, these observations indicate that this landscape was of terrestrial origin. Longitudinal profiles of ancient rivers were extracted and inverted for an uplift rate history. The best-fitting uplift rate history has three phases and total cumulative uplift of 350 m. Biostratigraphic data from surrounding marine stratigraphy indicate that this landscape formed within 1-1.5 Ma. This uplift history is similar to that of a slightly older buried landscape in the Faeroe-Shetland basin 400 km to the west. These records of vertical motion can explained by pulses of anomalously hot asthenosphere spreading out from the incipient Icelandic plume. Using simple isostatic calculations we estimate that the maximum thermal anomaly beneath Bressay was 50˚. Our observations suggest that a thermal anomaly departed the Icelandic plume as early as 58.5 Ma and had highest average temperatures at 55.6 Ma.

  14. Fluid flow and mud volcanism in the Eastern Mediterranean incipient collision zones

    Science.gov (United States)

    Zitter, T. A. C.; Woodside, J. M.; Mascle, J.

    2003-04-01

    Fluid venting activity, either coupled with mud volcanism or along deep active faults or both, has been investigated in the Eastern Mediterranean Sea, mainly in two areas associated with the incipient collision process between Africa and Eurasia. Mud volcanoes are abundant on the crestal part of the Mediterranean Ridge accretionary prism, in association with thrusts, back-thrusts and transcurrent features. They are also found in the Anaximander Mountains/Florence Rise area, to the west of Cyprus, where a wrench system accommodates the pre-collisional deformation. Combined swath multibeam bathymetry and imagery, seismic profiling (ANAXIPROBE survey, 1995 and PRISMED II survey, 1998) and O.R.E.Tech sidescan sonar data (MEDINETH survey, 1999) indicate the genetic relationship between mud volcanoes and tectonics, particularly potential influence of strike-slip faulting. The in situ observations of mud volcanoes (MEDINAUT survey, 1998) have revealed common characteristics at cold seeps, such as carbonate crust constructions and specific chemosynthetic-based fauna. Ground-truth of the sonar data shows that the geophysical signature of mud volcanoes may be related to spatial and temporal evolution of mud volcanism activity, because the seafloor characteristics (surface of the mud flows, distribution and nature of the crusts) and the degree of colonization by benthic fauna vary with the intensity and age of the fluid seepage. Moreover, clay mineralogy studies on the mud matrix samples give insights into the depositional environment, age, and depth of the lithological unit from which the mud breccia is extruded. The shallow signature of the mud reservoir tends to indicate that the overpressured fluids originate from deeper strata than the solid phase of the expelled material.

  15. Modified enthalpy method for the simulation of melting and ...

    Indian Academy of Sciences (India)

    ulate melting/solidification on a coarse grid and the temperature of a point close to the interface is plotted as a function of time, ... This function ensures that the viscosity of the solid is very large and approaches that of the molten liquid when f = 1. ...... transient dynamic fluid-structure interactions. Comput. Method Appl. M.

  16. Fugacity ratio estimations for high-melting rigid aromatic compounds.

    Science.gov (United States)

    Van Noort, Paul C M

    2004-07-01

    Prediction of the environmental fate of organic compounds requires knowledge of their tendency to stay in the gas and water phase. Vapor pressure and aqueous solubility are commonly used descriptors for these processes. Depending on the type of distribution process, values for either the pure solid state or the (subcooled) liquid state have to be used. Values for the (subcooled) liquid state can be calculated from those for the solid state, and vice versa, using the fugacity ratio. Fugacity ratios are usually calculated from the entropy of fusion and the melting point. For polycyclic aromatic hydrocarbons, chlorobenzenes, chlorodibenzofuranes, and chlorodibenzo(p)dioxins, fugacity ratios calculated using experimental entropies of fusion were systematically less than those obtained from a thermodynamically more rigorous approach using heat capacity data. The deviation was more than 1 order of magnitude at the highest melting point. The use of a universal value for the entropy of fusion of 56 J/molK resulted in either over or underestimation by up to more than 1 order of magnitude. A simple correction factor, based on the melting point only, was derived. This correction factor allowed the fugacity ratios to be estimated from experimental entropies of fusion and melting point with an accuracy better than 0.1-0.2 log units. Copyright 2004 Elsevier Ltd.

  17. Size-dependent melting of nanoparticles: Hundred years of ...

    Indian Academy of Sciences (India)

    point depression of nanoparticles and the variation is linear with the inverse of the particle size. An attempt to confirm this experimentally has been made first by. Pawlow [2] in 1910. Subsequently, other researchers [3–30] have investigated the variation of melting temperature with particle size and many theoretical models.

  18. Modified enthalpy method for the simulation of melting and ...

    Indian Academy of Sciences (India)

    The control volumes sharing a common face and having liquid fractions between 0 and 1 are identified. ... The constructed interface is then used to obtain geometric properties such as the centroids, the distances of ..... the centroid of the control volume which is undergoing a phase change is anchored at the melt- ing point.

  19. On melting dynamics and the glass transition. II. Glassy dynamics as a melting process.

    Science.gov (United States)

    Krzakala, Florent; Zdeborová, Lenka

    2011-01-21

    There are deep analogies between the melting dynamics in systems with a first-order phase transition and the dynamics from equilibrium in super-cooled liquids. For a class of Ising spin models undergoing a first-order transition--namely p-spin models on the so-called Nishimori line--it can be shown that the melting dynamics can be exactly mapped to the equilibrium dynamics. In this mapping the dynamical--or mode-coupling--glass transition corresponds to the spinodal point, while the Kauzmann transition corresponds to the first-order phase transition itself. Both in mean field and finite dimensional models this mapping provides an exact realization of the random first-order theory scenario for the glass transition. The corresponding glassy phenomenology can then be understood in the framework of a standard first-order phase transition.

  20. Numerical simulation of hot-melt extrusion processes for amorphous solid dispersions using model-based melt viscosity.

    Science.gov (United States)

    Bochmann, Esther S; Steffens, Kristina E; Gryczke, Andreas; Wagner, Karl G

    2018-03-01

    Simulation of HME processes is a valuable tool for increased process understanding and ease of scale-up. However, the experimental determination of all required input parameters is tedious, namely the melt rheology of the amorphous solid dispersion (ASD) in question. Hence, a procedure to simplify the application of hot-melt extrusion (HME) simulation for forming amorphous solid dispersions (ASD) is presented. The commercial 1D simulation software Ludovic ® was used to conduct (i) simulations using a full experimental data set of all input variables including melt rheology and (ii) simulations using model-based melt viscosity data based on the ASDs glass transition and the physical properties of polymeric matrix only. Both types of HME computation were further compared to experimental HME results. Variation in physical properties (e.g. heat capacity, density) and several process characteristics of HME (residence time distribution, energy consumption) among the simulations and experiments were evaluated. The model-based melt viscosity was calculated by using the glass transition temperature (T g ) of the investigated blend and the melt viscosity of the polymeric matrix by means of a T g -viscosity correlation. The results of measured melt viscosity and model-based melt viscosity were similar with only few exceptions, leading to similar HME simulation outcomes. At the end, the experimental effort prior to HME simulation could be minimized and the procedure enables a good starting point for rational development of ASDs by means of HME. As model excipients, Vinylpyrrolidone-vinyl acetate copolymer (COP) in combination with various APIs (carbamazepine, dipyridamole, indomethacin, and ibuprofen) or polyethylene glycol (PEG 1500) as plasticizer were used to form the ASDs. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Predicting the enthalpies of melting and vaporization for pure components

    Science.gov (United States)

    Esina, Z. N.; Korchuganova, M. R.

    2014-12-01

    A mathematical model of the melting and vaporization enthalpies of organic components based on the theory of thermodynamic similarity is proposed. In this empirical model, the phase transition enthalpy for the homological series of n-alkanes, carboxylic acids, n-alcohols, glycols, and glycol ethers is presented as a function of the molecular mass, the number of carbon atoms in a molecule, and the normal transition temperature. The model also uses a critical or triple point temperature. It is shown that the results from predicting the melting and vaporization enthalpies enable the calculation of binary phase diagrams.

  2. Dense Pure Tungsten Fabricated by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Dianzheng Wang

    2017-04-01

    Full Text Available Additive manufacturing using tungsten, a brittle material, is difficult because of its high melting point, thermal conductivity, and oxidation tendency. In this study, pure tungsten parts with densities of up to 18.53 g/cm3 (i.e., 96.0% of the theoretical density were fabricated by selective laser melting. In order to minimize balling effects, the raw polyhedral tungsten powders underwent a spheroidization process before laser consolidation. Compared with polyhedral powders, the spherical powders showed increased laser absorptivity and packing density, which helped in the formation of a continuous molten track and promoted densification.

  3. Lithium diffusion in silicate melts

    Science.gov (United States)

    Cunningham, G. J.; Henderson, P.; Lowry, R. K.; Nolan, J.; Reed, S. J. B.; Long, J. V. P.

    1983-10-01

    The diffusion properties of Li in an andesitic and pitchstone melt have been determined over the temperature range 1300-1400°C. The diffusion data have been fitted to an Arrhenius relationship between log D0 and 1/ T, and give relatively small activation energies of diffusion: 21.4±5.8 kcal mol -1 in the andesite and 20.1±2.8 kcal mol -1 in the pitchstone. Li +, unlike several other cations, shows similar diffusivities in these melt compositions to that in a basaltic melt. Despite the similar ionic radius of Li + to that of Co 2+, the diffusion properties of the two ions are very different from each other.

  4. Tipping Point

    Medline Plus

    Full Text Available ... en español Blog About OnSafety CPSC Stands for Safety The Tipping Point Home > 60 Seconds of Safety (Videos) > The Tipping Point The Tipping Point by ... danger death electrical fall furniture head injury product safety television tipover tv Watch the video in Adobe ...

  5. Population structure of guppies in north-eastern Venezuela, the area of putative incipient speciation.

    Science.gov (United States)

    Herdegen, Magdalena; Alexander, Heather J; Babik, Wiesław; Mavárez, Jesús; Breden, Felix; Radwan, Jacek

    2014-02-17

    Geographic barriers to gene flow and divergence among populations in sexual traits are two important causes of genetic isolation which may lead to speciation. Genetic isolation may be facilitated if these two mechanisms act synergistically. The guppy from the Cumaná region (within the Cariaco drainage) of eastern Venezuela has been previously described as a case of incipient speciation driven by sexual selection, significantly differentiated in sexual colouration and body shape from the common guppy, Poecilia reticulata. The latter occurs widely in northern Venezuela, including the south-eastern side of Cordillera de la Costa, where it inhabits streams belonging to the San Juan drainage. Here, we present molecular and morphological analyses of differentiation among guppy populations in the Cariaco and San Juan drainages. Our analyses are based on a 953 bp long mtDNA fragment, a set of 15 microsatellites (519 fish from 20 populations), and four phenotypic traits. Both microsatellite and mtDNA data showed that guppies inhabiting the two drainages are characterised by a significant genetic differentiation, but a higher proportion of the genetic variance was distributed among populations within regions. Most guppies in the Cariaco drainage had mtDNA from a distinct lineage, but we also found evidence for widespread introgression of mtDNA from the San Juan drainage into the Cariaco drainage. Phenotypically, populations in the two regions differed significantly only in the number of black crescents. Phenotypic clustering did not support existence of two distinct groupings, but indicated a degree of distinctiveness of Central Cumaná (CC) population. However, CC population showed little differentiation at the neutral markers from the proximate populations within the Cariaco drainage. Our findings are consistent with only partial genetic isolation between the two geographic regions and indicate that the geographic barrier of Cordillera de la Costa has not played an

  6. Challenges in Melt Furnace Tests

    Science.gov (United States)

    Belt, Cynthia

    2014-09-01

    Measurement is a critical part of running a cast house. Key performance indicators such as energy intensity, production (or melt rate), downtime (or OEE), and melt loss must all be understood and monitored on a weekly or monthly basis. Continuous process variables such as bath temperature, flue temperature, and furnace pressure should be used to control the furnace systems along with storing the values in databases for later analysis. While using measurement to track furnace performance over time is important, there is also a time and place for short-term tests.

  7. Melting processes of oligomeric α and β isotactic polypropylene crystals at ultrafast heating rates

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Xiaojing [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); He, Xuehao, E-mail: xhhe@tju.edu.cn, E-mail: scjiang@tju.edu.cn [Department of Chemistry, School of Science, Tianjin University, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Jiang, Shichun, E-mail: xhhe@tju.edu.cn, E-mail: scjiang@tju.edu.cn [School of Material, Tianjin University, Tianjin 300072 (China)

    2014-02-07

    The melting behaviors of α (stable) and β (metastable) isotactic polypropylene (iPP) crystals at ultrafast heating rates are simulated with atomistic molecular dynamics method. Quantitative information about the melting processes of α- and β-iPP crystals at atomistic level is achieved. The result shows that the melting process starts from the interfaces of lamellar crystal through random dislocation of iPP chains along the perpendicular direction of lamellar crystal structure. In the melting process, the lamellar crystal gradually expands but the corresponding thickness decreases. The analysis shows that the system expansion lags behind the crystallinity decreasing and the lagging extents for α- and β-iPP are significantly different. The apparent melting points of α- and β-iPP crystals rise with the increase of the heating rate and lamellar crystal thickness. The apparent melting point of α-iPP crystal is always higher than that of β-iPP at differently heating rates. Applying the Gibbs-Thomson rule and the scaling property of the melting kinetics, the equilibrium melting points of perfect α- and β-iPP crystals are finally predicted and it shows a good agreement with experimental result.

  8. Petrogenesis of incipient charnockite in the Ikalamavony sub-domain, south-central Madagascar: New insights from phase equilibrium modeling

    Science.gov (United States)

    Endo, Takahiro; Tsunogae, Toshiaki; Santosh, M.; Shaji, E.; Rambeloson, Roger A.

    2017-06-01

    Incipient charnockites representing granulite formation on a mesoscopic scale occur in the Ambodin Ifandana area of Ikalamavony sub-domain in south-central Madagascar. Here we report new petrological data from these rocks, and discuss the process of granulite formation on the basis of petrography, mineral equilibrium modeling, and fluid inclusion studies. The incipient charnockites occur as brownish patches, lenses, and layers characterized by an assemblage of biotite + orthopyroxene + K-feldspar + plagioclase + quartz + magnetite + ilmenite within host orthopyroxene-free biotite gneiss with an assemblage of biotite + K-feldspar + plagioclase + quartz + magnetite + ilmenite. Lenses and layers of calc-silicate rock (clinopyroxene + garnet + plagioclase + quartz + titanite + calcite) are typically associated with the charnockite. Coarse-grained charnockite occurs along the contact between the layered charnockite and calc-silicate rock. The application of mineral equilibrium modeling on the mineral assemblages in charnockite and biotite gneiss employing the NCKFMASHTO system as well as fluid inclusion study on coarse-grained charnockite defines a P-T range of 8.5-10.5 kbar and 880-900 °C, which is nearly consistent with the inferred P-T condition of the Ikalamavony sub-domain (8.0-10.5 kbar and 820-880 °C). The result of T versus H2O activity (a(H2O)) modeling demonstrates that orthopyroxene-bearing assemblage in charnockite is stable under relatively low a(H2O) condition of 0.42-0.43, which is consistent with the popular models of incipient-charnockite formation related to the lowering of water activity and stabilization of orthopyroxene through dehydration of biotite. The occurrence of calc-silicate rocks adjacent to the charnockite suggests that the CO2-bearing fluid that caused dehydration and incipient-charnockite formation might have been derived through decarbonation of calc-silicate rocks during the initial stage of decompression slightly after the peak

  9. Multivariate data analysis for finding the relevant fatty acids contributing to the melting fractions of cream

    DEFF Research Database (Denmark)

    Buldo, Patrizia; Larsen, Mette Krogh; Wiking, Lars

    2013-01-01

    : Multivariate analysis of data from individual cows identified the most relevant fatty acids contributing to the melting point of the medium melting fraction of cream. The fatty acid composition of milk fat could differentiate cream from different feeding strategies; however, owing to individual cow variation......BACKGROUND: The melting behaviour and fatty acid composition of cream from a total of 33 cows from four farms were analysed. Multivariate data analysis was used to identify the fatty acids that contributed most to the melting points and to differentiate between creams from different practical......:0 and palmitoleic acid (C16:1) in milk fat, whereas it decreased the amount of stearic acid (C18:0) and C18:1 trans fatty acid. Average data on the melting behaviour of cream separated the farms into two groups where the main differences in feeding were the amounts of maize silage and rapeseed cake used. CONCLUSION...

  10. Progress in Research on Green Lead-free Low-melting Sealing Glasses

    Directory of Open Access Journals (Sweden)

    HE Peng

    2016-06-01

    Full Text Available Traditional sealing glasses, which contain heavy metal Pb, posing threat to humans and environment, have been restricted or forbidden by most countries. Therefore, lead-free of low-melting sealing glasses will be the main future development direction. This article based on lead-free of low-melting sealing glasses, the main properties of low-melting sealing glasses were summarized. First, the composition, structural characteristics, performance and research status of several main low-melting sealing glasses, such as phosphate glass, borate glass, vanadate glass and bismuthate glass were introduced. Second, the low temperature and lead-free development directions were put forward. At last, regarding the shortcomings in the research of low-melting sealing glasses, it was pointed out that the future focused breaking points for research are composite doping modification, theoretical research on glass and new technology development of glass preparation.

  11. The infidelity of melt inclusions?

    Science.gov (United States)

    Kent, A. J.

    2008-12-01

    Melt inclusions provide important information about magmatic systems and represent unique records of magma composition and evolution. However, it is also clear that melt inclusions do not necessarily constitute a petrological 'magic bullet', and potential exists for trapped melt compositions to be modified by a range of inclusion-specific processes. These include trapping of diffusional boundary layers, crystallization of the host mineral after trapping and dissolution of co-trapped minerals during homogenization, diffusional exchange between trapped liquid and the host mineral and external melt, and cryptic alteration of trapped material during weathering or hydrothermal alteration. It clearly important to identify when melt inclusions are unmodified, and which compositional indices represent the most robust sources of petrogenetic information. In this presentation I review and discuss various approaches for evaluating compositions and compositional variations in inclusion suites. An overriding principle is that the variations evident in melt inclusions should be able to be understood in terms of petrological processes that are known, or can be reasonably inferred to also effect bulk magma compositions. One common approach is to base petrological conclusions on species that should be more robust, and many workers use variations in incompatible trace elements for this purpose. However important information may also be obtained from a comparison of variations in melt inclusions and the lavas that host them, and in most cases this comparison is the key to identifying inclusions and suites that are potentially suspect. Comparisons can be made between individual inclusions and lavas, although comparison of average inclusion composition and the host lava, after correction for differences in crystal fractionation, may also be valuable. An important extension of this is the comparison of the variability of different species in inclusions and host lavas. This also provides

  12. Effect of tellurium on viscosity and liquid structure of GaSb melts

    Energy Technology Data Exchange (ETDEWEB)

    Ji Leilei [School of Material Science and Engineering, Jinan University, Jinan 250022 (China); Geng Haoran [School of Material Science and Engineering, Jinan University, Jinan 250022 (China)], E-mail: mse_genghr@ujn.edu.cn; Sun Chunjing [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Teng Xinying; Liu Yamei [School of Material Science and Engineering, Jinan University, Jinan 250022 (China)

    2008-04-03

    The behavior of GaSb melt with tellurium addition was investigated using viscometer and differential scanning calorimetry (DSC). Normally, the viscosity of all melts measured decreased with the increasing temperature. However, anomalous transition points were observed in the temperature dependence of viscosity for Ga-Sb-Te system. Corresponded with the abnormal points on the viscosity-temperature curves, there were thermal effect peaks on the DSC curves. Furthermore, viscous activation energy and flow units of these melts and their structural features were discussed in this paper.

  13. Incipient boninitic arc crust built on denudated mantle: the Khantaishir ophiolite (western Mongolia)

    Science.gov (United States)

    Gianola, Omar; Schmidt, Max W.; Jagoutz, Oliver; Sambuu, Oyungerel

    2017-12-01

    The 570 Ma old Khantaishir ophiolite is built by up to 4 km harzburgitic mantle with abundant pyroxenites and dunites followed by 2 km of hornblende-gabbros and gabbronorites and by a 2.5 km thick volcanic unit composed of a dyke + sill complex capped by pillow lavas and some volcanoclastics. The volcanics are mainly basaltic andesites and andesites (or boninites) with an average of 58.2 ± 1.0 wt% SiO2, X Mg = 0.61 ± 0.03 ( X Mg = molar MgO/(MgO + FeOtot), TiO2 = 0.4 ± 0.1 wt% and CaO = 7.5 ± 0.6 wt% (errors as 2 σ). Normalized trace element patterns show positive anomalies for Pb and Sr, a negative Nb-anomaly, large ion lithophile elements (LILE) concentrations between N- and E-MORB and distinctly depleted HREE. These characteristics indicate that the Khantaishir volcanics were derived from a refractory mantle source modified by a moderate slab-component, similar to boninites erupted along the Izu-Bonin-Mariana subduction system and to the Troodos and Betts Cove ophiolites. Most strikingly and despite almost complete outcrops over 260 km2, there is no remnant of any pre-existing MORB crust, suggesting that the magmatic suite of this ophiolite formed on completely denudated mantle, most likely upon subduction initiation. The architecture of this 4-5 km thick early arc crust resembles oceanic crust formed at mid ocean ridges, but lacks a sheeted dyke complex; volcanic edifices are not observed. Nevertheless, low melting pressures combined with moderate H2O-contents resulted in high-Si primitive melts, in abundant hornblende-gabbros and in a fast enrichment in bulk SiO2. Fractional crystallization modeling starting from the observed primitive melts (56.6 wt% SiO2) suggests that 25 wt% pyroxene + plagioclase fractionation is sufficient to form the average Khantaishir volcanic crust. Most of the fractionation happened in the mantle, the observed pyroxenite lenses and layers in and at the top of the harzburgites account for the required cumulate volumes. Finally

  14. Fundamentals of Melt infiltration for the Preparation of Supported Metal Catalysts.The Case of Co/SiO2 Fischer-Tropsch Synthesis

    NARCIS (Netherlands)

    Eggenhuisen, T.M.|info:eu-repo/dai/nl/313959498; den Breejen, J.P.|info:eu-repo/dai/nl/304837318; Verdoes, D.; de Jongh, P.E.|info:eu-repo/dai/nl/186125372; de Jong, K.P.|info:eu-repo/dai/nl/06885580X

    2013-01-01

    We explored melt infiltration of mesoporous silica supports to prepare supported metal catalysts with high loadings and controllable particle sizes. Melting of Co(NO3)2 ·6H2O in the presence of silica supports was studied in situ with differential scanning calorimetry. The melting point depression

  15. Efficacy of 1.23% APF gel applications on incipient carious lesions: a double-blind randomized clinical trial

    Directory of Open Access Journals (Sweden)

    Maria Laura Menezes Bonow

    2013-06-01

    Full Text Available The aim of this double-blind randomized clinical trial was to evaluate the efficacy of 1.23% APF gel application on the arrest of active incipient carious lesions in children. Sixty 7- to 12-year-old children, with active incipient lesions were included in the study. Children were divided randomly into 2 groups: 1.23% APF gel and placebo gel applications. Each group received 8 weekly applications of treatment. The lesions were re-evaluated at the 4th and 8th appointments. Poisson regression analysis was used to estimate relative risks of the presence of active white spot lesions. Groups showed similar results (PR = 1.67; CI 95% 0.69–3.98. The persistence of at least 1 active lesion was associated with a higher number of lesions in the baseline (PR = 2.67; CI 95% 1.19–6.03, but not with sugar intake (PR = 1.06; CI 95% 0.56–2.86 and previous exposure to fluoride dentifrice (PR = 1.26; CI 95% 0.49–2.29. The trial demonstrates the equivalence of the treatments. The use of the APF gel showed no additional benefits in this sample of children exposed to fluoridated water and dentifrice. The professional dental plaque removal in both groups may also account for the resulting equivalence of the treatments.

  16. Tipping Point

    Medline Plus

    Full Text Available ... OnSafety CPSC Stands for Safety The Tipping Point Home > 60 Seconds of Safety (Videos) > The Tipping Point ... 24 hours a day. For young children whose home is a playground, it’s the best way to ...

  17. Fixed Points

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 5. Fixed Points - From Russia with Love - A Primer of Fixed Point Theory. A K Vijaykumar. Book Review Volume 5 Issue 5 May 2000 pp 101-102. Fulltext. Click here to view fulltext PDF. Permanent link:

  18. Alloying titanium and tantalum by cold crucible levitation melting (CCLM) furnace

    Energy Technology Data Exchange (ETDEWEB)

    Morita, A. [Fuji Electric Furnace Co., Ltd., Suzuka, Mie (Japan); Fukui, H. [Depart of Dental Materials, School of Dentistry, Aichi-Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya (Japan); Tadano, H.; Hayashi, S. [Fuji Electric Furnace Co., Ltd., 5520, Minami tamagaki-cho, Suzuka, Mie (Japan); Hasegawa, J. [Depart of Dental Materials, School of Dentistry, Aichi-Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya (Japan); Niinomi, M. [Department of Production Systems Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka, Tenpaku-cho, Toyohashi (Japan)

    2000-03-15

    Recently, titanium alloys have been studied as implant materials for dental and orthopedic surgery. Titanium alloys have distinguished characteristics of biocompatibility, corrosion resistance and mechanical properties. Having non-poisonous character to a living body, Ta, Zr and Nb have been used for addition to titanium alloys, which are free of vanadium and aluminum. It is well-known that titanium and tantalum are difficult metals to alloy in usual furnaces as these are very reactive metals, having great differences in melting point and specific gravity. To produce an alloy of titanium and tantalum, cold crucible levitation melting (CCLM) is effective in obtaining a uniform composition. Notable features of CCLM are that it can (1) melt metals with a high melting point, (2) create an alloy of uniform composition with a strong stirring effect by an electromagnetic force and (3) allow metals to be melted without contamination. We have melted 850 g of titanium and 150 g of tantalum by a CCLM furnace and have successfully made 1.0 kg of uniform composite Ti-15wt.% Ta alloy. It is noteworthy that the alloy was produced from pure base metals which were not alloyed beforehand and was made by a single melting (no re-melting) process. (orig.)

  19. SAXS study of transient pre-melting in chain-folded alkanes

    International Nuclear Information System (INIS)

    Ungar, G.; Wills, H.H.

    1990-01-01

    A pronounced pre-melting effect is observed in chain-folded crystals of pure monodisperse n-alkane C 246 H 494 . The effect is reversible on a short time scale, but at longer times the once-folded chain crystals are irreversibly lost as slow chain extension proceeds by solid diffusion well below the melting point. The melting process is thus monitored by rapid time-resolved small-angle X-ray (SAXS) measurements, using synchrotron radiation. The results show that the observed pronounced broadening of the DSC melting endotherm for chain-folded crystals is entirely due to genuine pre-melting of lamellar surfaces. Although a significant portion of material is already molten below the final melting point of chain-folded crystals T F , no recrystallization in the chain-extended form can occur until the cores of the crystalline lamellae melt at T F . Pre-melting of extended chain crystals is significantly less pronounced than that of folded chain crystals

  20. Grain boundary melting in ice

    OpenAIRE

    Thomson, E. S.; Hansen-Goos, Hendrik; Wilen, L. A.; Wettlaufer, J. S.

    2012-01-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentr...

  1. Tipping Point

    Medline Plus

    Full Text Available ... Point by CPSC Blogger September 22, 2009 appliance child Childproofing CPSC danger death electrical fall furniture head ... see news reports about horrible accidents involving young children and furniture, appliance and tv tip-overs. The ...

  2. Eutectic melting temperature of the lowermost Earth's mantle

    Science.gov (United States)

    Andrault, D.; Lo Nigro, G.; Bolfan-Casanova, N.; Bouhifd, M.; Garbarino, G.; Mezouar, M.

    2009-12-01

    Partial melting of the Earth's deep mantle probably occurred at different stages of its formation as a consequence of meteoritic impacts and seismology suggests that it even continues today at the core-mantle boundary. Melts are important because they dominate the chemical evolution of the different Earth's reservoirs and more generally the dynamics of the whole planet. Unfortunately, the most critical parameter, that is the temperature profile inside the deep Earth, remains poorly constrained accross the planet history. Experimental investigations of the melting properties of materials representative of the deep Earth at relevant P-T conditions can provide anchor points to refine past and present temperature profiles and consequently determine the degree of melting at the different geological periods. Previous works report melting relations in the uppermost lower mantle region, using the multi-anvil press [1,2]. On the other hand, the pyrolite solidus was determined up to 65 GPa using optical observations in the laser-heated diamond anvil cell (LH-DAC) [3]. Finally, the melting temperature of (Mg,Fe)2SiO4 olivine is documented at core-mantle boundary (CMB) conditions by shock wave experiments [4]. Solely based on these reports, experimental data remain too sparse to draw a definite melting curve for the lower mantle in the relevant 25-135 GPa pressure range. We reinvestigated melting properties of lower mantle materials by means of in-situ angle dispersive X-ray diffraction measurements in the LH-DAC at the ESRF [5]. Experiments were performed in an extended P-T range for two starting materials: forsterite and a glass with chondrite composition. In both cases, the aim was to determine the onset of melting, and thus the eutectic melting temperatures as a function of pressure. Melting was evidenced from drastic changes of diffraction peak shape on the image plate, major changes in diffraction intensities in the integrated pattern, disappearance of diffraction rings

  3. The surface quasiliquid melt acceleration and the role of thermodynamic phase in the thermal decomposition of crystalline organic explosives

    Energy Technology Data Exchange (ETDEWEB)

    Henson, Bryan F [Los Alamos National Laboratory

    2010-01-01

    We show that melt acceleration in the thermal decomposition of crystalline organic solids is a manifestation of the surface quasiliquid phase. We derive a single universal rate law for melt acceleration that is a simple function of the metastable liquid activity below the melting point, and has a zero order term proportional to the quasiliquid thickness. We argue that the underlying mechanisms of this model will provide a molecular definition for the stability of the class of secondary explosives.

  4. Direct contact heat transfer characteristics between melting alloy and water

    International Nuclear Information System (INIS)

    Kinoshita, Izumi; Nishi, Yoshihisa; Furuya, Masahiro

    1995-01-01

    As a candidate for an innovative steam generator for fast breeder reactors, a heat exchanger with direct contact heat transfer between melting alloy and water was proposed. The evaluation of heat transfer characteristics of this heat exchanger is one of the research subjects for the design and development of the steam generator. In this study, the effect of the pressure on heat transfer characteristics and the required degree of superheating of melting alloy above water saturation temperature are evaluated during the direct contact heat transfer experiment by injecting water into Wood's alloy. In the experiment, the pressure, the temperature of the Wood's alloy, the flow rate of feed water, and the depth of the feed water injection point are varied as parameters. As a result of the experiment, the product of the degree of Wood's alloy superheating above water saturation temperature and the depth of the feed water injection point is constant for each pressure. This constant increases as the pressure rises. (author)

  5. Melt-decontamination method for radioactive metal wastes

    International Nuclear Information System (INIS)

    Otsuka, Hisao; Izumida, Tatsuo; Kondo, Yasuo; Fujii, Norihisa; Tsuchiya, Hiroyuki.

    1997-01-01

    When metals contaminated by radioactive materials are melted by heating with addition of slugs, the weight ratio of basic slugs to acidic slugs constituting the molten slugs is controlled to from 0.5 to 0.3, and the transfer of radioactive materials in the molten metals to the slug phase is promoted. Then, Co, Ni and/or Cr as radioactive materials are removed. The temperature of the molten metals is controlled to higher than the melting point of the metals and lower than the decomposition point of oxides of the radioactive materials. With such procedures, not only Co but also a plurality of nuclides to be removed from the radioactive metal wastes can be decontaminated simultaneously, the operation is simplified and the amount of secondary wastes upon decontamination can be reduced. (T.M.)

  6. The Lund University Checklist for Incipient Exhaustion: a prospective validation of the onset of sustained stress and exhaustion warnings

    Directory of Open Access Journals (Sweden)

    Kai Österberg

    2016-09-01

    Full Text Available Abstract Background The need for instruments that can assist in detecting the prodromal stages of stress-related exhaustion has been acknowledged. The aim of the present study was to evaluate whether the Lund University Checklist for Incipient Exhaustion (LUCIE could accurately and prospectively detect the onset of incipient exhaustion and to what extent work stressor exposure and private burdens were associated with increasing LUCIE scores. Methods Using surveys, 1355 employees were followed for 11 quarters. Participants with prospectively elevated LUCIE scores were targeted by three algorithms entailing 4 quarters: (1 abrupt onset to a sustained Stress Warning (n = 18, (2 gradual onset to a sustained Stress Warning (n = 42, and (3 sustained Exhaustion Warning (n = 36. The targeted participants’ survey reports on changes in work situation and private life during the fulfillment of any algorithm criteria were analyzed, together with the interview data. Participants untargeted by the algorithms constituted a control group (n = 745. Results Eighty-seven percent of participants fulfilling any LUCIE algorithm criteria (LUCIE indication cases rated a negative change in their work situation during the 4 quarters, compared to 48 % of controls. Ratings of negative changes in private life were also more common in the LUCIE indication groups than among controls (58 % vs. 29 %, but free-text commentaries revealed that almost half of the ratings in the LUCIE indication groups were due to work-to-family conflicts and health problems caused by excessive workload, assigned more properly to work-related negative changes. When excluding the themes related to work-stress-related private life compromises, negative private life changes in the LUCIE indication groups dropped from 58 to 32 %, while only a negligible drop from 29 to 26 % was observed among controls. In retrospective interviews, 79 % of the LUCIE indication participants

  7. The Lund University Checklist for Incipient Exhaustion: a prospective validation of the onset of sustained stress and exhaustion warnings.

    Science.gov (United States)

    Österberg, Kai; Persson, Roger; Viborg, Njördur; Jönsson, Peter; Tenenbaum, Artur

    2016-09-29

    The need for instruments that can assist in detecting the prodromal stages of stress-related exhaustion has been acknowledged. The aim of the present study was to evaluate whether the Lund University Checklist for Incipient Exhaustion (LUCIE) could accurately and prospectively detect the onset of incipient exhaustion and to what extent work stressor exposure and private burdens were associated with increasing LUCIE scores. Using surveys, 1355 employees were followed for 11 quarters. Participants with prospectively elevated LUCIE scores were targeted by three algorithms entailing 4 quarters: (1) abrupt onset to a sustained Stress Warning (n = 18), (2) gradual onset to a sustained Stress Warning (n = 42), and (3) sustained Exhaustion Warning (n = 36). The targeted participants' survey reports on changes in work situation and private life during the fulfillment of any algorithm criteria were analyzed, together with the interview data. Participants untargeted by the algorithms constituted a control group (n = 745). Eighty-seven percent of participants fulfilling any LUCIE algorithm criteria (LUCIE indication cases) rated a negative change in their work situation during the 4 quarters, compared to 48 % of controls. Ratings of negative changes in private life were also more common in the LUCIE indication groups than among controls (58 % vs. 29 %), but free-text commentaries revealed that almost half of the ratings in the LUCIE indication groups were due to work-to-family conflicts and health problems caused by excessive workload, assigned more properly to work-related negative changes. When excluding the themes related to work-stress-related private life compromises, negative private life changes in the LUCIE indication groups dropped from 58 to 32 %, while only a negligible drop from 29 to 26 % was observed among controls. In retrospective interviews, 79 % of the LUCIE indication participants confirmed exclusively/predominantly work stressors

  8. String-like cooperative motion in homogeneous melting.

    Science.gov (United States)

    Zhang, Hao; Khalkhali, Mohammad; Liu, Qingxia; Douglas, Jack F

    2013-03-28

    Despite the fundamental nature and practical importance of melting, there is still no generally accepted theory of this ubiquitous phenomenon. Even the earliest simulations of melting of hard discs by Alder and Wainwright indicated the active role of collective atomic motion in melting and here we utilize molecular dynamics simulation to determine whether these correlated motions are similar to those found in recent studies of glass-forming (GF) liquids and other condensed, strongly interacting, particle systems. We indeed find string-like collective atomic motion in our simulations of "superheated" Ni crystals, but other observations indicate significant differences from GF liquids. For example, we observe neither stretched exponential structural relaxation, nor any decoupling phenomenon, while we do find a boson peak, findings that have strong implications for understanding the physical origin of these universal properties of GF liquids. Our simulations also provide a novel view of "homogeneous" melting in which a small concentration of interstitial defects exerts a powerful effect on the crystal stability through their initiation and propagation of collective atomic motion. These relatively rare point defects are found to propagate down the strings like solitons, driving the collective motion. Crystal integrity remains preserved when the permutational atomic motions take the form of ring-like atomic exchanges, but a topological transition occurs at higher temperatures where the rings open to form linear chains similar in geometrical form and length distribution to the strings of GF liquids. The local symmetry breaking effect of the open strings apparently destabilizes the local lattice structure and precipitates crystal melting. The crystal defects are thus not static entities under dynamic conditions, such as elevated temperatures or material loading, but rather are active agents exhibiting a rich nonlinear dynamics that is not addressed in conventional "static

  9. Bubble Formation in Basalt-like Melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Keding, Ralf; Yue, Yuanzheng

    2011-01-01

    The effect of the melting temperature on bubble size and bubble formation in an iron bearing calcium aluminosilicate melt is studied by means of in-depth images acquired by optical microscopy. The bubble size distribution and the total bubble volume are determined by counting the number of bubbles...... and their diameter. The variation in melting temperature has little influence on the overall bubble volume. However, the size distribution of the bubbles varies with the melting temperature. When the melt is slowly cooled, the bubble volume increases, implying decreased solubility of the gaseous species. Mass...

  10. Anomalous melting behavior of solid hydrogen at high pressures

    OpenAIRE

    Liu, Hanyu; Hernández, Eduardo R.; Yan, Jun; Ma, Yanming

    2013-01-01

    Hydrogen is the most abundant element in the universe, and its properties under conditions of high temperature and pressure are crucial to understand the interior of of large gaseous planets and other astrophysical bodies. At ultra high pressures solid hydrogen has been predicted to transform into a quantum fluid, because of its high zero point motion. Here we report first principles two phase coexistence and Z method determinations of the melting line of solid hydrogen in a pressure range sp...

  11. A method of heat accumulation and a direct-contact latent melting heat thermal accumulator

    International Nuclear Information System (INIS)

    Cachard, Maurice de; Goffinet, Pierre; Kurka, Gerard; Bricard, Alain; Morrachioli, Robert.

    1974-01-01

    The invention relates to a method for the accumulation of heat, and to a direct-contact latent melting-heat thermal accumulator. According to the invention, a coolant fluid F is caused to be in direct contact with a material C having a high latent melting-heat, said fluid F and material C being in heat exchange relationship at a temperature in the vicinity of the melting point of C, whereby, when hot fluid F is caused to be in direct contact with material C, the later will melt and store heat in the form of latent melting-heat while cooling fluid F, and when cold fluid F is caused to be in direct contact with material C, the latter will solidify by transferring heat to fluid F. This can be applied to the manufacturing of heat-exchangers for coupling an electric power-station to a distribution network [fr

  12. Simulation and measurement of melting effects on metal sheets caused by direct lightning strikes

    Science.gov (United States)

    Kern, Alexander

    1991-01-01

    Direct lightning strikes melt metal parts of various systems, like fuel and propellant tanks of rockets and airplanes, at the point of strike. Responsible for this melting are the impulse current and, if occurring, the long duration current, both carrying a remarkable charge Q. For studying these meltings the simulation in the laboratory has to be based on the parameters of natural lightnings. International standards exist defining certain threat levels of natural lightnings and giving possible generator circuits for the simulation. The melting caused by both types of lightning currents show different appearance. Their characteristics, their differences in melting and heating of metal sheets are investigated. Nevertheless the simulation of lightning in the laboratory is imperfect. While natural lightning is a discharge without a counter electrode, the simulation always demands a close counter electrode. The influence of this counter electrode is studied.

  13. Industrial opportunities of controlled melt flow during glass melting, part 1: Melt flow evaluation

    Czech Academy of Sciences Publication Activity Database

    Dyrčíková, Petra; Hrbek, Lukáš; Němec, Lubomír

    2014-01-01

    Roč. 58, č. 2 (2014), s. 111-117 ISSN 0862-5468 R&D Projects: GA TA ČR TA01010844 Institutional support: RVO:67985891 Keywords : glass melting * controlled flow * space utilization Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.435, year: 2014 http://www.ceramics-silikaty.cz/2014/pdf/2014_02_111.pdf

  14. Incipient crystallization of transition-metal tungstates under microwaves probed by Raman scattering and transmission electron microscopy

    International Nuclear Information System (INIS)

    Siqueira, Kisla P. F.; Dias, Anderson

    2011-01-01

    Microwave synthesis was used to produce nanosized transition-metal tungstates in environmentally friendly conditions not yet reported by the literature: 110 and 150 °C, for times of 10 and 20 min. X-ray diffraction evidenced incipient crystallized materials, while transmission electron microscopy indicates nanostructured regions of about 2–5 nm inside an amorphous matrix. Raman spectroscopy was used to probe short-range ordering in the achieved samples and also to obtain a reliable set of spectra containing all the Raman-active bands predicted by group-theory calculations. The vibrational spectra showed no extra feature, indicating that the microwave processing was able to produce short-range ordered materials without tetrahedral distortions. These distortions are frequently reported when commercially modified kitchen microwave units are employed. In this work, the syntheses were conducted in a commercial apparatus especially designed for fully controlled temperature–time–pressure conditions.

  15. Incipient colonisation of Lutzomyia longipalpis in the city of Resistencia, province of Chaco, Argentina (2010-2012).

    Science.gov (United States)

    Szelag, Enrique Alejandro; Parras, Matías Ariel; Fabiani, Mariela; Rosa, Juan Ramón; Salomón, Oscar Daniel

    2014-07-01

    Lutzomyia longipalpis was recorded for the first time in Argentina in 2004, in the province of Formosa. In the following years, the vector spread to the south and west in the country and was recorded in the province of Chaco in 2010. From November 2010-May 2012, captures of Phlebotominae were made in the city of Resistencia and its surroundings, to monitor the spread and possible colonisation of Lu. longipalpis in the province of Chaco. In this monitoring, Lu. longipalpis was absent in urban sampling sites and its presence was restricted to Barrio de los Pescadores. This suggests that the incipient colonisation observed in 2010 was not followed by continuous installation of vector populations and expansion of their spatial distribution as in other urban centres of Argentina.

  16. Structure of Cd-Ga melts. Pt. 2

    International Nuclear Information System (INIS)

    Hermann, G.; Rainer-Harbach, G.; Steeb, S.

    1980-01-01

    X-ray small-angle scattering experiments were performed on nine melts of the Cd-Ga system at different temperatures up to 440 0 C. Evaluation of the data follows the Ornstein-Zernike theory of critical scattering, thus yielding correlation lengths xi of concentration fluctuations and the long-wavelenght limit Ssub(C)sub(C)(0) of the Bhatia-Thornton structure factor. Studies of the concentration and temperature dependence of xi and Ssub(C)sub(C)(0) indicate that the critical point occurs at csub(c) = 50.0 +- 1.0 at% Ga and Tsub(c) = 295.2 +- 0.1 0 C. For a melt with the critical concentration, Ssub(C)sub(C)(0) increases up to 3500 times the ideal Ssup(i)sup(d)sub(c)sub(c)(0) = csub(A)csub(B). This indicates a strong segregation tendency. In the vicinity of the critical point of the Cd-Ga system, experimental correlation lengths xi > 100 Angstroem were obtained. The critical-point exponents ν and γ were determined. It follows that the behaviour of a critical Cd-Ga melt satisfies the prediction of the classical mean-field theory for higher temperatures, whereas, within experimental accuracy, the lattice-gas predictions are satisfied upon approaching the critical temperature. (orig.)

  17. Studies on Al-Cu-Li-Mg-Ag-Zr alloy processed through vacuum induction melting (VIM) technique

    International Nuclear Information System (INIS)

    Nayan, Niraj; Govind; Nair, K. Suseelan; Mittal, M.C.; Sudhakaran, K.N.

    2007-01-01

    A new technique of lithium addition has been adapted for the processing of Al-Cu-Li-Ag-Mg-Zr alloy, which gives more than 90% recovery of lithium throughout the billet. Processing studies on this alloy include casting, three step homogenization, to avoid incipient melting, and mechanical working particularly forging and rolling. The products in the form of sheets were subjected to various T6 (solution treatment + water quenching + aging) tempers. Mechanical properties were evaluated at room temperature and correlated with microstructure. Characterizations using optical microscope and post-fracture analysis have been carried out using Scanning electron microscope (SEM). Experimental investigation shows highest mechanical properties for the Al-1.3%Li alloy in T6 (500 deg. C/1 h + WQ + 190 deg. C/24 h) condition

  18. ELM-induced transient tungsten melting in the JET divertor

    Science.gov (United States)

    Coenen, J. W.; Arnoux, G.; Bazylev, B.; Matthews, G. F.; Autricque, A.; Balboa, I.; Clever, M.; Dejarnac, R.; Coffey, I.; Corre, Y.; Devaux, S.; Frassinetti, L.; Gauthier, E.; Horacek, J.; Jachmich, S.; Komm, M.; Knaup, M.; Krieger, K.; Marsen, S.; Meigs, A.; Mertens, Ph.; Pitts, R. A.; Puetterich, T.; Rack, M.; Stamp, M.; Sergienko, G.; Tamain, P.; Thompson, V.; Contributors, JET-EFDA

    2015-02-01

    The original goals of the JET ITER-like wall included the study of the impact of an all W divertor on plasma operation (Coenen et al 2013 Nucl. Fusion 53 073043) and fuel retention (Brezinsek et al 2013 Nucl. Fusion 53 083023). ITER has recently decided to install a full-tungsten (W) divertor from the start of operations. One of the key inputs required in support of this decision was the study of the possibility of W melting and melt splashing during transients. Damage of this type can lead to modifications of surface topology which could lead to higher disruption frequency or compromise subsequent plasma operation. Although every effort will be made to avoid leading edges, ITER plasma stored energies are sufficient that transients can drive shallow melting on the top surfaces of components. JET is able to produce ELMs large enough to allow access to transient melting in a regime of relevance to ITER. Transient W melt experiments were performed in JET using a dedicated divertor module and a sequence of IP = 3.0 MA/BT = 2.9 T H-mode pulses with an input power of PIN = 23 MW, a stored energy of ˜6 MJ and regular type I ELMs at ΔWELM = 0.3 MJ and fELM ˜ 30 Hz. By moving the outer strike point onto a dedicated leading edge in the W divertor the base temperature was raised within ˜1 s to a level allowing transient, ELM-driven melting during the subsequent 0.5 s. Such ELMs (δW ˜ 300 kJ per ELM) are comparable to mitigated ELMs expected in ITER (Pitts et al 2011 J. Nucl. Mater. 415 (Suppl.) S957-64). Although significant material losses in terms of ejections into the plasma were not observed, there is indirect evidence that some small droplets (˜80 µm) were released. Almost 1 mm (˜6 mm3) of W was moved by ˜150 ELMs within 7 subsequent discharges. The impact on the main plasma parameters was minor and no disruptions occurred. The W-melt gradually moved along the leading edge towards the high-field side, driven by j × B forces. The evaporation rate determined

  19. Measuring melting capacity with calorimetry

    OpenAIRE

    Betten, Linda

    2014-01-01

    Road salting is an important aspect of winter maintenance. There has been an increase in the usage of salt in later years to keep the road safe and accessible. It is a desire to reduce the amount of salt due to environmental aspects. To achieve better practices for winter maintenance it is necessary to obtain more knowledge about the different properties of salt. The motivation for this thesis is to develop a better method for determining the melting capacity for salt, which is an important p...

  20. Eruption style at Kīlauea Volcano in Hawai‘i linked to primary melt composition

    Science.gov (United States)

    Sides. I.R.,; Edmonds, M.; Maclennan, J.; Swanson, Don; Houghton, Bruce F.

    2014-01-01

    Explosive eruptions at basaltic volcanoes have been linked to gas segregation from magmas at shallow depths in the crust. The composition of primary melts formed at greater depths was thought to have little influence on eruptive style. Ocean island basaltic volcanoes are the product of melting of a geochemically heterogeneous mantle plume and are expected to give rise to heterogeneous primary melts. This range in primary melt composition, particularly with respect to the volatile components, will profoundly influence magma buoyancy, storage and eruption style. Here we analyse the geochemistry of a suite of melt inclusions from 25 historical eruptions at the ocean island volcano of Kīlauea, Hawai‘i, over the past 600 years. We find that more explosive styles of eruption at Kīlauea Volcano are associated statistically with more geochemically enriched primary melts that have higher volatile concentrations. These enriched melts ascend faster and retain their primary nature, undergoing little interaction with the magma reservoir at the volcano’s summit. We conclude that the eruption style and magma-supply rate at Kīlauea are fundamentally linked to the geochemistry of the primary melts formed deep below the volcano. Magmas might therefore be predisposed towards explosivity right at the point of formation in their mantle source region.

  1. Retrieving original melt compositions in migmatites

    Science.gov (United States)

    Kriegsman, L. M.; Nyström, A. I.

    2003-04-01

    The final textures and mineral modes of anatectic migmatites are affected by four successive processes: (i) prograde partial melting and small-scale segregation into melt-rich domains and restitic domains; (ii) partial melt extraction; (iii) partial retrograde reactions (back reaction) between in situ crystallizing melt and the restite; (iv) crystallization of remaining melt at the water-saturated solidus, releasing volatiles (Kriegsman, 2001). These processes are investigated using mass balance calculations in the KFMASH chemical system. Starting from a fixed bulk composition, fluid-absent melting reactions are considered along an isobaric heating path, followed by mineral-melt reactions during isobaric cooling (path 1), and uplift (path 2). Variables in the model are the restite fraction X and the melt fraction Y involved in back reaction, the melt fraction Z extracted from the system, and the melt fraction 1-Y-Z crystallized in situ at the water-saturated solidus. Incongruent phases are considered to be part of the restite. To facilitate calculations, mineral and melt compositions are taken to be constant. It is shown that melanosome, leucosome, and mesosome compositions generally do not show linear compositional trends in a closed system. Instead, mesosome, neosome, protolith and melt compositions lie on a hyperplane and form linear trends in any compositional diagram. Several methods are proposed to retrieve the melt composition from neosome and mesosome compositions. Applications to natural examples (dataset of Ashworth, 1976; and our new data from SW Finland) strengthen the migmatite-to-granite connection which may notably be obscured by the back reaction process. References: Kriegsman, L.M., 2001, Lithos 56, 75-96 Ashworth, J.R., 1976. Mineralogical Magazine 40, 661-682

  2. Melting curve of compressed barium carbonate from in situ ionic conductivity measurements: Implications for the melting behavior of alkaline earth carbonates in Earth's deep carbon cycle

    Science.gov (United States)

    Dong, J.; Li, J.; Zhu, F.; Li, Z.; Farawi, R.

    2017-12-01

    The whereabouts of subducted carbonates place a major constraint on the Earth's deep carbon cycle, but the fraction of carbon retained in the slab and transported into the deep mantle, compared to that released from the slab and recycled to the surface, is still under debate. Knowledge of the stability of carbonated mantle rocks is pivotal for assessing the ability of slabs to carry carbonates into the deep mantle. Determination and systematic comparison of the melting curves of alkali and alkaline earth carbonates at high pressure can help construct thermodynamic models to predict the melting behavior of complex carbonated mantle rocks. Among alkaline earth carbonates, the melting behavior of barium carbonate (BaCO3) has not been adequately understood. The reported melting point of BaCO3at 1 bar differ by nearly 800 °C and constraints on the melting curve of BaCO3 at high pressure are not available. In this study, the melting temperatures of BaCO3 were determined up to 11 GPa from in situ ionic conductivity measurements using the multi-anvil apparatus at the University of Michigan. The solid-liquid boundary at high pressure was detected on the basis of a steep rise in conductivity through the sample upon melting. The melting point of BaCO3 was found to drop from 1797 °C at 3.3 GPa to 1600 °C at 5.5 GPa and then rise with pressure to 2180 °C at 11 GPa. The observed melting depression point at 5.5 GPa corresponds to the phase transition of BaCO3 from the aragonite structure (Pmcn) to post-aragonite structure (Pmmn) at 6.3 GPa, 877 °C and 8.0 GPa, 727 °C, determined from synchrotron X-ray diffraction measurements using laser-heated DAC experiments at the Advanced Photon Source, Argonne National Laboratory. These results are also compared with ex situ falling marker experiments, and the three methods together place tight constraints on the melting curve of BaCO3 and elucidates the effect of structural phase transitions on its melting behavior.

  3. Experimental and theoretical evidence for bilayer-by-bilayer surface melting of crystalline ice

    DEFF Research Database (Denmark)

    Sánchez, M. Alejandra; Kling, Tanja; Ishiyama, Tatsuya

    2017-01-01

    On the surface of water ice, a quasi-liquid layer (QLL) has been extensively reported at temperatures below its bulk melting point at 273 K. Approaching the bulk melting temperature from below, the thickness of the QLL is known to increase. To elucidate the precise temperature variation of the QLL......, and its nature, we investigate the surface melting of hexagonal ice by combining noncontact, surfacespecific vibrational sum frequency generation (SFG) spectroscopy and spectra calculated from molecular dynamics simulations. Using SFG, we probe the outermost water layers of distinct single crystalline ice...

  4. Point defects in hard-sphere crystals

    NARCIS (Netherlands)

    Pronk, S.; Frenkel, D.

    2001-01-01

    We report numerical calculations of the concentration of interstitials in hard-sphere crystals. We find that in a three-dimensional fcc hard-sphere crystal at the melting point, the concentration of interstitials is 2.7(4) × 10-8. This is some 3 orders of magnitude lower than the concentration of

  5. Monitoring of polymer melt processing

    International Nuclear Information System (INIS)

    Alig, Ingo; Steinhoff, Bernd; Lellinger, Dirk

    2010-01-01

    The paper reviews the state-of-the-art of in-line and on-line monitoring during polymer melt processing by compounding, extrusion and injection moulding. Different spectroscopic and scattering techniques as well as conductivity and viscosity measurements are reviewed and compared concerning their potential for different process applications. In addition to information on chemical composition and state of the process, the in situ detection of morphology, which is of specific interest for multiphase polymer systems such as polymer composites and polymer blends, is described in detail. For these systems, the product properties strongly depend on the phase or filler morphology created during processing. Examples for optical (UV/vis, NIR) and ultrasonic attenuation spectra recorded during extrusion are given, which were found to be sensitive to the chemical composition as well as to size and degree of dispersion of micro or nanofillers in the polymer matrix. By small-angle light scattering experiments, process-induced structures were detected in blends of incompatible polymers during compounding. Using conductivity measurements during extrusion, the influence of processing conditions on the electrical conductivity of polymer melts with conductive fillers (carbon black or carbon nanotubes) was monitored. (topical review)

  6. Chemical decontamination and melt densification

    International Nuclear Information System (INIS)

    Dillon, R.L.; Griggs, B.; Kemper, R.S.; Nelson, R.G.

    1976-01-01

    Preliminary studies on the chemical decontamination and densification of Zircaloy, stainless steel, and Inconel undissolved residues remaining after dissolution of the UO 2 --PuO 2 spent fuel material from sheared fuel bundles are reported. The studies were made on cold or very small samples to demonstrate the feasibility of the processes developed before proceeding to hot cell demonstrations with kg level of the sources. A promising aqueous decontamination method for Zr alloy cladding was developed in which oxidized surfaces are conditioned with HF prior to leaching with ammonium oxalate, ammonium citrate, ammonium fluoride, and hydrogen peroxide. Feasibility of molten salt decontamination of oxidized Zircaloy was demonstrated. A low melting alloy of Zircaloy, stainless steel, and Inconel was obtained in induction heated graphite crucibles. Segregated Zircaloy cladding sections were directly melted by the inductoslag process to yield a metal ingot suitable for storage. Both Zircaloy and Zircaloy--stainless steel--Inconel alloys proved to be highly satisfactory getters and sinks for recovered tritium

  7. Viscosity model for aluminosilicate melt

    Directory of Open Access Journals (Sweden)

    Zhang G.H.

    2012-01-01

    Full Text Available The structurally based viscosity model proposed in our previous study is extended to include more components, e.g. SiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O and K2O. A simple method is proposed to calculate the numbers of different types of oxygen ions classified by the different cations they bonded with, which is used to characterize the influence of composition on viscosity. When dealing with the aluminosilicate melts containing several basic oxides, the priority order is established for different cations for charge compensating Al3+ ions, according to the coulombic force between cation and oxygen anion. It is indicated that basic oxides have two paradox influences on viscosity: basic oxide with a higher basicity decreases viscosity more greatly by forming weaker non-bridging oxygen bond; while it increases viscosity more greatly by forming stronger bridging oxygen bond in tetrahedron after charge compensating Al3+ ion. The present model can extrapolate its application range to the system without SiO2. Furthermore, it could also give a satisfy interpretation to the abnormal phenomenon that viscosity increases when adding K2O to CaO-Al2O3-SiO2 melt within a certain composition range.

  8. Sound propagation in selenium and tellurium melts

    International Nuclear Information System (INIS)

    Glazov, V.M.; Kim, S.G.; Sulejmenov, T.

    1989-01-01

    Methods, that under similar frequences of ten MHz and using one sample permit to study temperature dependences and propagation velocities, the absorption coefficient of the sound in melts, are described. As a result studying selenium and tellurium melts intricate polytherms of sound propagation velocity and absorption coefficient, that are interpreted usiung representations on breaking chains in associated liquid(selenium) and dissolution of short chains in the melt(tellurium) atomic matrix, are constructed

  9. Direct writing by way of melt electrospinning.

    Science.gov (United States)

    Brown, Toby D; Dalton, Paul D; Hutmacher, Dietmar W

    2011-12-15

    Melt electrospun fibers of poly(ϵ-caprolactone) are accurately deposited using an automated stage as the collector. Matching the translation speed of the collector to the speed of the melt electrospinning jet establishes control over the location of fiber deposition. In this sense, melt electrospinning writing can be seen to bridge the gap between solution electrospinning and direct writing additive manufacturing processes. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Melting phenomena: effect of composition for 55-atom Ag-Pd bimetallic clusters.

    Science.gov (United States)

    Cheng, Daojian; Wang, Wenchuan; Huang, Shiping

    2008-05-14

    Understanding the composition effect on the melting processes of bimetallic clusters is important for their applications. Here, we report the relationship between the melting point and the metal composition for the 55-atom icosahedral Ag-Pd bimetallic clusters by canonical Monte Carlo simulations, using the second-moment approximation of the tight-binding potentials (TB-SMA) for the metal-metal interactions. Abnormal melting phenomena for the systems of interest are found. Our simulation results reveal that the dependence of the melting point on the composition is not a monotonic change, but experiences three different stages. The melting temperatures of the Ag-Pd bimetallic clusters increase monotonically with the concentration of the Ag atoms first. Then, they reach a plateau presenting almost a constant value. Finally, they decrease sharply at a specific composition. The main reason for this change can be explained in terms of the relative stability of the Ag-Pd bimetallic clusters at different compositions. The results suggest that the more stable the cluster, the higher the melting point for the 55-atom icosahedral Ag-Pd bimetallic clusters at different compositions.

  11. Surface melting of deuterium hydride thick films

    OpenAIRE

    Zeppenfeld, P.; Bienfait, M.; Feng Chuan Liu,; Vilches, O.E.; Coddens, G.

    1990-01-01

    Quasi-elastic neutron scattering has been used to measure, below the bulk melting temperature, the thickness and the diffusion coefficient of the mobile surface layer of 8 and 10 layer thick films of deuterium hydride (HD) condensed on MgO(100). The measurements show that the close-packed surface of solid HD surface melts gradually, with the thickness of the melted layer increasing from 0.5 to 6 molecular layers as the temperature rises from 4 K to 0.05 K below the bulk melting temperature. T...

  12. Grain boundary melting in ice

    Science.gov (United States)

    Thomson, E. S.; Hansen-Goos, Hendrik; Wettlaufer, J. S.; Wilen, L. A.

    2013-03-01

    We describe an optical scattering study of grain boundary premelting in water ice. Ubiquitous long ranged attractive polarization forces act to suppress grain boundary melting whereas repulsive forces originating in screened Coulomb interactions and classical colligative effects enhance it. The liquid enhancing effects can be manipulated by adding dopant ions to the system. For all measured grain boundaries this leads to increasing premelted film thickness with increasing electrolyte concentration. Although we understand that the interfacial surface charge densities qs and solute concentrations can potentially dominate the film thickness, we cannot directly measure them within a given grain boundary. Therefore, as a framework for interpreting the data we consider two appropriate qs dependent limits; one is dominated by the colligative effect and other is dominated by electrostatic interactions.

  13. Electrolysis of simulated lunar melts

    Science.gov (United States)

    Lewis, R. H.; Lindstrom, D. J.; Haskin, L. A.

    1985-01-01

    Electrolysis of molten lunar soil or rock is examined as an attractive means of wresting useful raw materials from lunar rocks. It requires only hat to melt the soil or rock and electricity to electrolyze it, and both can be developed from solar power. The conductivities of the simple silicate diopside, Mg CaSi2O6 were measured. Iron oxide was added to determine the effect on conductivity. The iron brought about substantial electronic conduction. The conductivities of simulated lunar lavas were measured. The simulated basalt had an AC conductivity nearly a fctor of two higher than that of diopside, reflecting the basalt's slightly higher total concentration of the 2+ ions Ca, Mg, and Fe that are the dominant charge carriers. Electrolysis was shown to be about 30% efficient for the basalt composition.

  14. A Unified Theory of Melting, Crystallization and Glass Formation

    DEFF Research Database (Denmark)

    Cotterill, R. M. J.; Jensen, F. J.; Damgaard Kristensen, W.

    1975-01-01

    In recent years, dislocations have been involved in theories of melting, in models of the liquid state, and in calculations of the viscosity of glasses. Particularly noteworthy are the Mott-Gurney model of a liquid as a polycrystal with a grain size (i. e. a dislocation network size) of near......-atomic dimensions, and the demonstration by Kotze and Kuhlmann-Wilsdorf that the solid-liquid interfacial energy is proportional to the grain boundary energy for a number of elements. These developments suggest the possibility of a relatively simple picture of crystallization and glass formation. In the liquid...... state dislocations, at the saturation density, are in constant motion and the microscopic grain boundary structure that they form is constantly changing due to dislocation-dislocation interaction. As the liquid is cooled below the melting point the free energy favors the crystalline form and grains...

  15. Devitrification of defense nuclear waste glasses: role of melt insolubles

    International Nuclear Information System (INIS)

    Bickford, D.F.; Jantzen, C.M.

    1985-01-01

    Time-temperature-transformation (TTT) curves have been determined for simulated nuclear waste glasses bounding the compositional range in the Defense Waste Processing Facility (DWPF). Formulations include all of the minor chemical elements such as ruthenium and chromium which have limited solubility in borosilicate glasses. Heterogeneous nucleation of spinel on ruthenium dioxide, and subsequent nucleation of acmite on spinel is the major devitrification path. Heterogeneous nucleation on melt insolubles causes more rapid growth of crystalline devitrification phases, than in glass free of melt insolubles. These studies point out the importance of simulating waste glass composition and processing as accurately as possible to obtain reliable estimates of glass performance. 11 refs., 8 figs., 1 tab

  16. Melting and glass transition of radiation-induced graft polyethylene

    International Nuclear Information System (INIS)

    Toi, K.; Kikuchi, M.; Tokuda, T.

    1977-01-01

    Melting and glass transition data are reported employing DSC for styrene-grafted high-density polyethylene obtained by γ radiation. Judging from the data of the melting point and the heat of fusion, the grafted polystyrene had no effect on the polyethylene crystallites, but the half-width of the thermogram was observed to increase slightly, showing an effect on the crystallite size distribution. As no effect was observed on the glass transition temperature by grafting, the amorphous region of the polyethylene apparently was not affected. It is suggested, therefore, that the free volume or segmental mobility will not be decreased by radiation-induced grafting. Very few but long grafted chains had negligible effect on the average polyethylene chain length available for segmental motion, and grafted polystyrene should be expected to differ from the styrene homopolymer in thermal motions

  17. Melting and solidification of bismuth inclusions in aluminium

    DEFF Research Database (Denmark)

    Thoft, N.B.; Bohr, J.; Buras, B.

    1995-01-01

    Supercooling of crystalline bismuth inclusions in aluminium crystals has been observed and studied with different techniques: x-ray diffraction, in situ Rutherford backscattering/channelling spectrometry and transmission electron microscopy. The results of the measurements with different experime......Supercooling of crystalline bismuth inclusions in aluminium crystals has been observed and studied with different techniques: x-ray diffraction, in situ Rutherford backscattering/channelling spectrometry and transmission electron microscopy. The results of the measurements with different...... experimental methods (and on different samples) agree remarkably well. The inclusions melt at temperatures at or below the bismuth bulk melting point, and the solid/liquid phase transition exhibits a hysteresis of 100-150 K. Average inclusion sizes ranged from a few nm to some tens of nm. The x-ray diffraction...

  18. Mycobacterium tuberculosis thymidylate kinase antigen assays for designating incipient, high-risk latent M.tb infection.

    Science.gov (United States)

    Wayengera, Misaki; Kateete, David P; Asiimwe, Benon; Joloba, Moses L

    2018-03-16

    Precise designation of high risk forms of latent Mycobacterium tuberculosis-M.tb infections (LTBI) is impossible. Delineation of high-risk LTBI can, however, allow for chemoprophylaxis and curtail majority cases of active tuberculosis (ATB). There is epidemiological evidence to support the view that LTBI in context of HIV-1 co-infection is high-risk for progression to ATB relative to LTBI among HIV-ve persons. We recently showed that assays of M.tb thymidylate kinase (TMKmt) antigen and host specific IgG can differentiate ATB from LTBI and or no TB (NTB, or healthy controls). In this study, we aimed to expose the differential levels of TMKmt Ag among HIV+ve co-infected LTBI relative to HIV-ve LTBI as a strategy to advance these assays for designating incipient LTBI. TMKmt host specific IgM and IgG detection Enzyme Immuno-Assays (EIA) were conducted on 40 TB exposed house-hold contacts (22 LTBI vs. 18 no TB (NTB) by QunatiFERON-TB GOLD®); and TMKmt Ag detection EIA done on 82 LTBI (46 HIV+ve vs 36 HIV-ve) and 9 NTB (American donors). Purified recombinant TMKmt protein was used as positive control for the Ag assays. IgM levels were found to be equally low across QuantiFERON-TB GOLD® prequalified NTB and TB exposed house-hold contacts. Higher TMKmt host specific IgG trends were found among TB house-hold contacts relative to NTB controls. TMKmt Ag levels among HIV+ve LTBI were 0.2676 ± 0.0197 (95% CI: 0.2279 to 0.3073) relative to 0.1069 ± 0.01628 (95% CI: 0.07385 to 0.14) for HIV-ve LTBI (supporting incipient nature of LTBI in context of HIV-1 co-infection). NTB had TMKmt Ag levels of 0.1013 ± 0.02505 (5% CI: 0.0421 to 0.1606) (intimating that some were indeed LTBI). TMKmt Ag levels represent a novel surrogate biomarker for high-risk LTBI, while host-specific IgG can be used to designate NTB from LTBI.

  19. The interaction of a vortex ring with a sloped sediment layer: Critical criteria for incipient grain motion

    Science.gov (United States)

    Munro, R. J.

    2012-02-01

    Experiments were performed to analyse the interaction between a vortex ring and a sloped sediment layer. Attention focussed on interactions under "critical" conditions, in which sediment motion was only just induced by the ring's flow field. Both hydraulically smooth and hydraulically rough bedforms were analysed, using near-spherical monodisperse sediments with relative densities of 1.2 and 2.5 and mean diameters (dp) ranging between 80 and 1087 μm. Measurements of the vortex-ring flow field were obtained, during the interaction, using two-dimensional particle imaging velocimetry. The threshold conditions for incipient sediment motion were analysed in terms of the critical Shields parameter (Nc), defined in terms of the peak tangential velocity measured adjacent to the bed surface. Bed-slope effects were investigated by tilting the sediment layer at various angles between the horizontal and the repose limit for the sediment. In all cases, the propagation axis of the vortex ring was aligned normal to the bed surface. The measured values of Nc were compared with a force-balance model based on the conditions for incipient grain motion on a sloping bed. For hydraulically smooth bedforms, where the bed roughness is small compared to the boundary-layer depth, the model was derived to account for how viscous stresses affect the drag and lift forces acting on the near surface sediment. For hydraulically rough bedforms, where this viscous-damping effect is not present, the model assumes the drag and lift forces scale with the square of the near-bed (inviscid) velocity scale. In both cases, the model predicts that bedforms become more mobile as the bed slope is increased. However, the damping effect of the viscous sublayer acts as a stabilizing influence for hydraulically smooth bedforms, to reduce the rate at which the bed mobility increases with bed slope. The measured values of Nc were in agreement with the trends predicted by this model, and exhibit a transition in

  20. Mitochondrial DNA evidences reflect an incipient population structure in Atlantic goliath grouper (Epinephelus itajara, Epinephelidae in Brazil

    Directory of Open Access Journals (Sweden)

    Júnio S. Damasceno

    2015-12-01

    Full Text Available The Atlantic goliath grouper is a critically endangered species that inhabits estuarine and reef environments and is threatened primarily by fishing activities and habitat destruction. Despite the urgent need for protection, its genetic conservation status remains unknown. The aim of the present study was to evaluate the gene flow among the populations of the species along the coast of Brazil based on the control region of the mitochondrial DNA. The results indicate low haplotype diversity (0.40-0.86 and very low nucleotide diversity (0.1-0.5%. They also show that the genetic diversity of the species varies considerably along the coast and that this finding may be especially important for the identification of priority areas for its conservation. The population analyses indicate a low but significant degree of genetic structuring (ΦST =0.111, probably due to the occurrence of rare haplotypes at some locations, although the genetic differentiation between sites was not correlated with geographic distance (r=0.0501; p=0.7719, and the shared haplotypes indicate that gene flow occurs among all locations along the Brazilian coast. The results of the pairwise FST indicate a high degree of genetic differentiation between locations. The incipient population structuring detected in the present study is not related systematically to the geological or physical features of the Brazilian coast. The complex interaction of fluctuations in sea level, marine currents, and the reproductive characteristics of the species hampers the identification of the specific role of each of these processes in the gene flow dynamics of the population units of the Atlantic goliath grouper. The low overall levels of genetic diversity, the pairwise FST values and the significant population structuring among groups (ΦCT identified in the present study all reinforce the critically endangered status of the species and are inconsistent with the presence of a single, panmictic

  1. Reaction of soda-lime-silica glass melt with water vapour at melting temperatures

    Czech Academy of Sciences Publication Activity Database

    Vernerová, Miroslava; Kloužek, Jaroslav; Němec, Lubomír

    2015-01-01

    Roč. 416, MAY 15 (2015), s. 21-30 ISSN 0022-3093 R&D Projects: GA TA ČR TA01010844 Institutional support: RVO:67985891 Keywords : glass melt * sulfate * water vapour * bubble nucleation * melt foaming * glass melting Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.825, year: 2015

  2. Size-dependent melting modes and behaviors of Ag nanoparticles: a molecular dynamics study

    Science.gov (United States)

    Liang, Tianshou; Zhou, Dejian; Wu, Zhaohua; Shi, Pengpeng

    2017-12-01

    The size-dependent melting behaviors and mechanisms of Ag nanoparticles (NPs) with diameters of 3.5–16 nm were investigated by molecular dynamics (MD). Two distinct melting modes, non-premelting and premelting with transition ranges of about 7–8 nm, for Ag NPs were demonstrated via the evolution of distribution and transition of atomic physical states during annealing. The small Ag NPs (3.5–7 nm) melt abruptly without a stable liquid shell before the melting point, which is characterized as non-premelting. A solid-solid crystal transformation is conducted through the migration of adatoms on the surface of Ag NPs with diameters of 3.5–6 nm before the initial melting, which is mainly responsible for slightly increasing the melting point of Ag NPs. On the other hand, surface premelting of Ag NPs with diameters of 8–16 nm propagates from the outer shell to the inner core with initial anisotropy and late isotropy as the temperature increases, and the close-packed facets {111} melt by a side-consumed way which is responsible for facets {111} melting in advance relative to the crystallographic plane {111}. Once a stable liquid shell is formed, its size-independent minimum thickness is obtained, and a three-layer structure of atomic physical states is set up. Lastly, the theory of point defect-pair (vacancy-interstitial) severing as the mechanism of formation and movement of the solid-liquid interface was also confirmed. Our study provides a basic understanding and theoretical guidance for the research, production and application of Ag NPs.

  3. Incipient offending among schizophrenia patients after first contact to the psychiatric hospital system

    DEFF Research Database (Denmark)

    Munkner, Runa; Haastrup, Soeren; Joergensen, Torben

    2005-01-01

    The study examines how age, sex and substance use disorder are associated with the risk of committing a criminal offence. The study explicitly examines the risk after the first contact to the psychiatric hospital system and after the diagnosis of schizophrenia for those with no previous criminal...... record; the association between previous non-violent criminality and later violent criminality is also analysed. The study sample comprised 4619 individuals ever diagnosed with schizophrenia. All solved offences were accessible. Data were analysed using Cox's regression. Schizophrenic men had twice....... Previous non-violent criminality increased the risk for later violent criminality 2.5- to 2.7-fold, depending on the starting point for the analyses. The results suggest that the psychiatric treatment system can play an active role in preventing criminality among individuals with schizophrenia...

  4. Incipient offending among schizophrenia patients after first contact to the psychiatric hospital system

    DEFF Research Database (Denmark)

    Munkner, Runa; Haastrup, Soeren; Joergensen, Torben

    2005-01-01

    The study examines how age, sex and substance use disorder are associated with the risk of committing a criminal offence. The study explicitly examines the risk after the first contact to the psychiatric hospital system and after the diagnosis of schizophrenia for those with no previous criminal...... record; the association between previous non-violent criminality and later violent criminality is also analysed. The study sample comprised 4619 individuals ever diagnosed with schizophrenia. All solved offences were accessible. Data were analysed using Cox's regression. Schizophrenic men had twice...... the risk of schizophrenic women of committing both violent and non-violent offences. A registered substance use disorder increased the risk 1.9- to 3.7-fold, depending on the starting point for the analyses, while increasing age on first contact or when diagnosed with schizophrenia diminished the risk...

  5. Permeability and 3-D melt geometry in shear-induced high melt fraction conduits

    Science.gov (United States)

    Zhu, W.; Cordonnier, B.; Qi, C.; Kohlstedt, D. L.

    2017-12-01

    Observations of dunite channels in ophiolites and uranium-series disequilibria in mid-ocean ridge basalt suggest that melt transport in the upper mantle beneath mid-ocean ridges is strongly channelized. Formation of high melt fraction conduits could result from mechanical shear, pyroxene dissolution, and lithological partitioning. Deformation experiments (e.g. Holtzman et al., 2003) demonstrate that shear stress causes initially homogeneously distributed melt to segregate into an array of melt-rich bands, flanked by melt-depleted regions. At the same average melt fraction, the permeability of high melt fraction conduits could be orders of magnitude higher than that of their homogenous counterparts. However, it is difficult to determine the permeability of melt-rich bands. Using X-ray synchrotron microtomography, we obtained high-resolution images of 3-dimensional (3-D) melt distribution in a partially molten rock containing shear-induced high melt fraction conduits. Sample CQ0705, an olivine-alkali basalt aggregate with a nominal melt fraction of 4%, was deformed in torsion at a temperature of 1473 K and a confining pressure of 300 MPa to a shear strain of 13.3. A sub-volume of CQ0705 encompassing 3-4 melt-rich bands was imaged. Microtomography data were reduced to binary form so that solid olivine is distinguishable from basalt glass. At a spatial resolution of 160 nm, the 3-D images reveal the shape and connectedness of melt pockets in the melt-rich bands. Thin melt channels formed at grain edges are connected at large melt nodes at grain corners. Initial data analysis shows a clear preferred orientation of melt pockets alignment subparallel to the melt-rich band. We use the experimentally determined geometrical parameters of melt topology to create a digital rock with identical 3-D microstructures. Stokes flow simulations are conducted on the digital rock to obtain the permeability tensor. Using this digital rock physics approach, we determine how deformation

  6. Disordering and Melting of Aluminum Surfaces

    DEFF Research Database (Denmark)

    Stoltze, Per; Nørskov, Jens Kehlet; Landman, U.

    1988-01-01

    We report on a molecular-dynamics simulation of an Al(110) surface using the effective-medium theory to describe the interatomic interactions. The surface region is found to start melting ≅200 K below the bulk melting temperature with a gradual increase in the thickness of the disordered layer as...

  7. Recent Changes in the Arctic Melt Season

    Science.gov (United States)

    Stroeve, Julienne; Markus, Thorsten; Meier, Walter N.; Miller, Jeff

    2007-01-01

    Melt-season duration, melt-onset and freeze-up dates are derived from satellite passive microwave data and analyzed from 1979 to 2005 over Arctic sea ice. Results indicate a shift towards a longer melt season, particularly north of Alaska and Siberia, corresponding to large retreats of sea ice observed in these regions. Although there is large interannual and regional variability in the length of the melt season, the Arctic is experiencing an overall lengthening of the melt season at a rate of about 2 weeks decade(sup -1). In fact, all regions in the Arctic (except for the central Arctic) have statistically significant (at the 99% level or higher) longer melt seasons by greater than 1 week decade(sup -1). The central Arctic shows a statistically significant trend (at the 98% level) of 5.4 days decade(sup -1). In 2005 the Arctic experienced its longest melt season, corresponding with the least amount of sea ice since 1979 and the warmest temperatures since the 1880s. Overall, the length of the melt season is inversely correlated with the lack of sea ice seen in September north of Alaska and Siberia, with a mean correlation of -0.8.

  8. Heterozygote PCR product melting curve prediction.

    Science.gov (United States)

    Dwight, Zachary L; Palais, Robert; Kent, Jana; Wittwer, Carl T

    2014-03-01

    Melting curve prediction of PCR products is limited to perfectly complementary strands. Multiple domains are calculated by recursive nearest neighbor thermodynamics. However, the melting curve of an amplicon containing a heterozygous single-nucleotide variant (SNV) after PCR is the composite of four duplexes: two matched homoduplexes and two mismatched heteroduplexes. To better predict the shape of composite heterozygote melting curves, 52 experimental curves were compared with brute force in silico predictions varying two parameters simultaneously: the relative contribution of heteroduplex products and an ionic scaling factor for mismatched tetrads. Heteroduplex products contributed 25.7 ± 6.7% to the composite melting curve, varying from 23%-28% for different SNV classes. The effect of ions on mismatch tetrads scaled to 76%-96% of normal (depending on SNV class) and averaged 88 ± 16.4%. Based on uMelt (www.dna.utah.edu/umelt/umelt.html) with an expanded nearest neighbor thermodynamic set that includes mismatched base pairs, uMelt HETS calculates helicity as a function of temperature for homoduplex and heteroduplex products, as well as the composite curve expected from heterozygotes. It is an interactive Web tool for efficient genotyping design, heterozygote melting curve prediction, and quality control of melting curve experiments. The application was developed in Actionscript and can be found online at http://www.dna.utah.edu/hets/. © 2013 WILEY PERIODICALS, INC.

  9. Recharging "Hot-Melt" Adhesive Film

    Science.gov (United States)

    Progar, D. J.

    1983-01-01

    Technique for recharging surface with "hot-melt" film makes use of one sided, high-temperature, pressure-sensitive adhesive tape. Purpose of the one-sided tape is to hold hot-melt charge in place until fused to surface. After adhesive has fused to surface and cooled, tape is removed, leaving adhesive on surface.

  10. Summer Melts Immigrant Students' College Plans

    Science.gov (United States)

    Naranjo, Melissa M.; Pang, Valerie Ooka; Alvarado, Jose Luis

    2016-01-01

    Many college-intending students find themselves dealing with the undermatch and summer melt phenomena. Undermatch refers to the situation where academically-successful high-school graduates choose not to go to any college or to go to a local community college not commensurate with their academic achievements. Summer melt describes how students may…

  11. Modeling the summertime evolution of sea-ice melt ponds

    DEFF Research Database (Denmark)

    Lüthje, Mikael; Feltham, D.L.; Taylor, P.D.

    2006-01-01

    We present a mathematical model describing the summer melting of sea ice. We simulate the evolution of melt ponds and determine area coverage and total surface ablation. The model predictions are tested for sensitivity to the melt rate of unponded ice, enhanced melt rate beneath the melt ponds...

  12. Shape evolution of a melting nonspherical particle.

    Science.gov (United States)

    Kintea, Daniel M; Hauk, Tobias; Roisman, Ilia V; Tropea, Cameron

    2015-09-01

    In this study melting of irregular ice crystals was observed in an acoustic levitator. The evolution of the particle shape is captured using a high-speed video system. Several typical phenomena have been discovered: change of the particle shape, appearance of a capillary flow of the melted liquid on the particle surface leading to liquid collection at the particle midsection (where the interface curvature is smallest), and appearance of sharp cusps at the particle tips. No such phenomena can be observed during melting of spherical particles. An approximate theoretical model is developed which accounts for the main physical phenomena associated with melting of an irregular particle. The agreement between the theoretical predictions for the melting time, for the evolution of the particle shape, and the corresponding experimental data is rather good.

  13. Melting Can Hinder Impact-Induced Adhesion

    Science.gov (United States)

    Hassani-Gangaraj, Mostafa; Veysset, David; Nelson, Keith A.; Schuh, Christopher A.

    2017-10-01

    Melting has long been used to join metallic materials, from welding to selective laser melting in additive manufacturing. In the same school of thought, localized melting has been generally perceived as an advantage, if not the main mechanism, for the adhesion of metallic microparticles to substrates during a supersonic impact. Here, we conduct the first in situ supersonic impact observations of individual metallic microparticles aimed at the explicit study of melting effects. Counterintuitively, we find that under at least some conditions melting is disadvantageous and hinders impact-induced adhesion. In the parameter space explored, i.e., ˜10 μ m particle size and ˜1 km /s particle velocity, we argue that the solidification time is much longer than the residence time of the particle on the substrate, so that resolidification cannot be a significant factor in adhesion.

  14. Study on plasma melting treatment of crucibles, ceramic filter elements, asbestos, and fly ash

    International Nuclear Information System (INIS)

    Hoshi, Akiko; Nakasio, Nobuyuki; Nakajima, Mikio

    2004-01-01

    The Japan Atomic Energy Research Institute (JAERI) decided to adopt an advanced volume reduction program for low-level radioactive wastes. In this program, inorganic wastes are converted to stable glassy products suitable for disposal by a plasma melting system in the Waste Volume Reduction Facilities (WVRF). High melting point wastes such as refractories are excluded from the plasma melting treatment in the WVRF, and wastes difficult to handle such as asbestos are also excluded. However, it is describable to apply the plasma melting treatment to these wastes for stabilization and volume reduction from the viewpoint of disposal. In this paper, plasma melting test of crucibles, ceramic filter elements, asbestos, and simulated fly ashes were carried out as a part of technical support for WVRF. The plasma melting treatment was applicable for crucibles and asbestos because homogeneous and glassy products were obtained by controlling of waste and loading condition. It was found that SiC in ceramic filter elements was volatile with a plasma torch with inert gas, and adding reducer was ineffective against stabilizing volatile metals such as Zn, Pb in a solidified product in the melting test of simulated fly ash. (author)

  15. Volatile diffusion in silicate melts and its effects on melt inclusions

    Directory of Open Access Journals (Sweden)

    P. Scarlato

    2005-06-01

    Full Text Available A compendium of diffusion measurements and their Arrhenius equations for water, carbon dioxide, sulfur, fluorine, and chlorine in silicate melts similar in composition to natural igneous rocks is presented. Water diffusion in silicic melts is well studied and understood, however little data exists for melts of intermediate to basic compositions. The data demonstrate that both the water concentration and the anhydrous melt composition affect the diffusion coefficient of water. Carbon dioxide diffusion appears only weakly dependent, at most, on the volatilefree melt composition and no effect of carbon dioxide concentration has been observed, although few experiments have been performed. Based upon one study, the addition of water to rhyolitic melts increases carbon dioxide diffusion by orders of magnitude to values similar to that of 6 wt% water. Sulfur diffusion in intermediate to silicic melts depends upon the anhydrous melt composition and the water concentration. In water-bearing silicic melts sulfur diffuses 2 to 3 orders of magnitude slower than water. Chlorine diffusion is affected by both water concentration and anhydrous melt composition; its values are typically between those of water and sulfur. Information on fluorine diffusion is rare, but the volatile-free melt composition exerts a strong control on its diffusion. At the present time the diffusion of water, carbon dioxide, sulfur and chlorine can be estimated in silicic melts at magmatic temperatures. The diffusion of water and carbon dioxide in basic to intermediate melts is only known at a limited set of temperatures and compositions. The diffusion data for rhyolitic melts at 800°C together with a standard model for the enrichment of incompatible elements in front of growing crystals demonstrate that rapid crystal growth, greater than 10-10 ms-1, can significantly increase the volatile concentrations at the crystal-melt interface and that any of that melt trapped

  16. Melt Rate Improvement for DWPF MB3: Melt Rate Furnace Testing

    Energy Technology Data Exchange (ETDEWEB)

    Stone, M.E.

    2001-07-24

    The Defense Waste Processing Facility (DWPF) would like to increase its canister production rate. The goal of this study is to improve the melt rate in DWPF specifically for Macrobatch 3. However, the knowledge gained may result in improved melting efficiencies translating to future DWPF macrobatches and in higher throughput for other Department of Energy's (DOE) melters. Increased melting efficiencies decrease overall operational costs by reducing the immobilization campaign time for a particular waste stream. For melt rate limited systems, a small increase in melting efficiency translates into significant hard dollar savings by reducing life cycle operational costs.

  17. Evaluation of Alternative Atomistic Models for the Incipient Growth of ZnO by Atomic Layer Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Manh-Hung; Tian, Liang; Chaker, Ahmad; Skopin, Evgenii; Cantelli, Valentina; Ouled, Toufik; Boichot, Raphaël; Crisci, Alexandre; Lay, Sabine; Richard, Marie-Ingrid; Thomas, Olivier; Deschanvres, Jean-Luc; Renevier, Hubert; Fong, Dillon; Ciatto, Gianluca

    2017-03-20

    ZnO thin films are interesting for applications in several technological fields, including optoelectronics and renewable energies. Nanodevice applications require controlled synthesis of ZnO structures at nanometer scale, which can be achieved via atomic layer deposition (ALD). However, the mechanisms governing the initial stages of ALD had not been addressed until very recently. Investigations into the initial nucleation and growth as well as the atomic structure of the heterointerface are crucial to optimize the ALD process and understand the structure-property relationships for ZnO. We have used a complementary suite of in situ synchrotron x-ray techniques to investigate both the structural and chemical evolution during ZnO growth by ALD on two different substrates, i.e., SiO2 and Al2O3, which led us to formulate an atomistic model of the incipient growth of ZnO. The model relies on the formation of nanoscale islands of different size and aspect ratio and consequent disorder induced in the Zn neighbors' distribution. However, endorsement of our model requires testing and discussion of possible alternative models which could account for the experimental results. In this work, we review, test, and rule out several alternative models; the results confirm our view of the atomistic mechanisms at play, which influence the overall microstructure and resulting properties of the final thin film.

  18. [Study on fluidized melt-granulation. I. Examination of the factors on the granulation].

    Science.gov (United States)

    Haramiishi, Y; Kitazawa, Y; Sakai, M; Kataoka, K

    1991-09-01

    The purpose of this study is to develop a new granulation method by using a fluidized-bed granulator, which requires a nucleus with a low melting point as a binder. This method was named as fluidized melt-granulation. The technique is very simple and useful. In this paper, the granulation mechanism and the effect of the physico-chemical properties of raw materials on the growth of the granules were investigated. The results were as follows: (1) The mixture of the nucleus and the other powder particles was heated up to the melting point of the nucleus by hot inlet air, immediately resulting in the generation of the adhesion of the powders on the melted nucleus. The granules grew as the melted material immersed into the void space among the adhered particles. (2) The lower the viscosity of the melted nucleus was, the faster the granule grew. (3) The shape and the size of the nucleus affected those of the products. (4) The optimum mixing ratio between the nucleus and the granulated materials existed and it depended on the ratio between the surface areas of these materials.

  19. Effects of Melt Processing on Evolution of Structure in PEEK

    Science.gov (United States)

    Georgiev, Georgi; Dai, Patrick Shuanghua; Oyebode, Elizabeth; Cebe, Peggy; Capel, Malcolm

    1999-01-01

    We report on the effects of melt processing temperature on structure formation in Poly(ether-ether-ketone), PEEK. Real time Small Angle X-ray Scattering, SAXS, and thermal analysis are used to follow the melting behavior after various stages of processing. Assignment of peaks to structural entities within the material, the relative perfection of the crystals, and the possibility of their reorganization, are all influenced by the melt processing history. With the advent of high intensity synchrotron sources of X-radiation, polymer scientists gain a research tool which, when used along with thermal analysis, provides additional structural information about the crystals during growth and subsequent melting. PEEK is an engineering thermoplastic polymer with a very high glass transition temperature (145 C) and crystal melting point (337 C). PEEK has been the subject of recent studies by X-ray scattering in which melt and cold crystallization were followed in real-time. X-ray scattering and thermal studies have been used to address the formation of dual endothermic response which has been variously ascribed to lamellar insertion, dual crystal populations, or melting followed by re-crystallization. Another important issue is whether all of the amorphous phase is located in interlamellar regions, or alternatively whether some is located in "pockets" away from the crystalline lamellar stacks. The interpretation of scattering from lamellar stacks varies depending upon whether such amorphous pockets are formed. Some groups believe all of the amorphous phase is interlamellar. This leads to selection of a smaller thickness for the crystals. Other groups suggest that most amorphous phase is not interlamellar, and this leads to the suggestion that the crystal thickness is larger than the amorphous layer within the stacks. To investigate these ideas, we used SAXS and Differential Scanning Calorimetry to compare results of single and dual stage melt crystallization of PEEK using a

  20. Terrestrial impact melt rocks and glasses

    Science.gov (United States)

    Dressler, B. O.; Reimold, W. U.

    2001-12-01

    The effects of meteorite and comet impact on Earth are rock brecciation, the formation of shock metamorphic features, rock melting, and the formation of impact structures, i.e. simple craters, complex craters, and multi-ring basins. Large events, such as the 65-Ma Chicxulub impact, are believed to have had catastrophic environmental effects that profoundly influenced the development of life on Earth. In this review, an attempt is made to summarize some of the voluminous literature on impact melting, one important aspect of planetary impact, provide some comments on this process, and to make suggestions for future research. The products of impact melting are glasses, impact melt rocks, and pseudotachylites. Our treatise deals mainly with the geological setting, petrography, and major-element chemistry of melt rocks and glasses. Impact glasses, in several petrographic aspects, are similar to volcanic glasses, but they are associated with shock metamorphosed mineral and rock fragments and, in places, with siderophile element anomalies suggestive of meteoritic contamination. They are found in allogenic breccia deposits within (fall-back 'suevite') and outside (fall-out 'suevite') impact craters and, as spherules, in distal ejecta. Large events, such as the K/T boundary Chicxulub impact, are responsible for the formation of worldwide ejecta horizons which are associated with siderophile element anomalies and shock metamorphosed mineral and rock debris. Impact glasses have a bulk chemical composition that is homogeneous but exemptions to this rule are common. On a microscopic scale, however, impact glasses are commonly strikingly heterogeneous. Tektites are glasses ejected from craters over large distances. They are characterized by very low water and volatile contents and element abundances and ratios that are evidence that tektites formed by melting of upper crustal, sedimentary rocks. Four tektite strewn-fields are known, three of which can be tied to specific impact

  1. Experimental testing of olivine-melt equilibrium models at high temperatures

    Science.gov (United States)

    Krasheninnikov, S. P.; Sobolev, A. V.; Batanova, V. G.; Kargaltsev, A. A.; Borisov, A. A.

    2017-08-01

    Data are presented on the equilibrium compositions of olivine and melts in the products of 101 experiments performed at 1300-1600°C, atmospheric pressure, and controlled oxygen fugacity by means of new equipment at the Vernadsky Institute. It was shown that the available models of the olivine-melt equilibrium describe with insufficient adequacy the natural systems at temperatures over 1400°C. The most adequate is the model by Ford et al. (1983). However, this model overestimates systematically the equilibrium temperature with underestimating by 20-40°C at 1450-1600°C. These data point to the need for developing a new, improved quantitative model of the olivine-melt equilibrium for high-temperature magnesian melts, as well as to the possibility of these studies on the basis of the equipment presented.

  2. Melting of iron at the Earth's core conditions by molecular dynamics simulation

    Directory of Open Access Journals (Sweden)

    Y. N. Wu

    2011-09-01

    Full Text Available By large scale molecular dynamics simulations of solid-liquid coexistence, we have investigated the melting of iron under pressures from 0 to 364 GPa. The temperatures of liquid and solid regions, and the pressure of the system are calculated to estimate the melting point of iron. We obtain the melting temperature of iron is about 6700±200K under the inner-outer core boundary, which is in good agreement with the result of Alfè et al. By the pair analysis technique, the microstructure of liquid iron under higher pressures is obviously different from that of lower pressures and ambient condition, indicating that the pressure-induced liquid-liquid phase transition may take place in iron melts.

  3. Movement of liquid beryllium during melt events in JET with ITER-like wall

    International Nuclear Information System (INIS)

    Sergienko, G; Huber, A; Brezinsek, S; Coenen, J W; Mertens, Ph; Philipps, V; Samm, U; Arnoux, G; Matthews, G F; Nunes, I; Riccardo, V; Sirinelli, A; Devaux, S

    2014-01-01

    The ITER-like wall recently installed in JET comprises solid beryllium limiters and a combination of bulk tungsten and tungsten-coated carbon fibre composite divertor tiles without active cooling. During a beryllium power handling qualification experiment performed in limiter configuration with 5 MW neutral beam injection input power, accidental beryllium melt events, melt layer motion and splashing were observed locally on a few beryllium limiters in the plasma contact areas. The Lorentz force is responsible for the observed melt layer movement. To move liquid beryllium against the gravity force, the current flowing from the plasma perpendicularly to the limiter surface must be higher than 6 kA m −2 . The thermo-emission current at the melting point of beryllium is much lower. The upward motion of the liquid beryllium against gravity can be due to a combination of the Lorentz force from the secondary electron emission and plasma pressure force. (paper)

  4. MELTING, a flexible platform to predict the melting temperatures of nucleic acids

    Directory of Open Access Journals (Sweden)

    Dumousseau Marine

    2012-05-01

    Full Text Available Abstract Background Computing accurate nucleic acid melting temperatures has become a crucial step for the efficiency and the optimisation of numerous molecular biology techniques such as in situ hybridization, PCR, antigene targeting, and microarrays. MELTING is a free open source software which computes the enthalpy, entropy and melting temperature of nucleic acids. MELTING 4.2 was able to handle several types of hybridization such as DNA/DNA, RNA/RNA, DNA/RNA and provided corrections to melting temperatures due to the presence of sodium. The program can use either an approximative approach or a more accurate Nearest-Neighbor approach. Results Two new versions of the MELTING software have been released. MELTING 4.3 is a direct update of version 4.2, integrating newly available thermodynamic parameters for inosine, a modified adenine base with an universal base capacity, and incorporates a correction for magnesium. MELTING 5 is a complete reimplementation which allows much greater flexibility and extensibility. It incorporates all the thermodynamic parameters and corrections provided in MELTING 4.x and introduces a large set of thermodynamic formulae and parameters, to facilitate the calculation of melting temperatures for perfectly matching sequences, mismatches, bulge loops, CNG repeats, dangling ends, inosines, locked nucleic acids, 2-hydroxyadenines and azobenzenes. It also includes temperature corrections for monovalent ions (sodium, potassium, Tris, magnesium ions and commonly used denaturing agents such as formamide and DMSO. Conclusions MELTING is a useful and very flexible tool for predicting melting temperatures using approximative formulae or Nearest-Neighbor approaches, where one can select different sets of Nearest-Neighbor parameters, corrections and formulae. Both versions are freely available at http://sourceforge.net/projects/melting/and at http://www.ebi.ac.uk/compneur-srv/melting/under the terms of the GPL license.

  5. Viscosity of ring polymer melts

    KAUST Repository

    Pasquino, Rossana

    2013-10-15

    We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes, and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts η0,linear to their ring counterparts η0,ring at isofrictional conditions is discussed as a function of the number of entanglements Z. In the unentangled regime η0,linear/η 0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation η0,linear/ η0,ring = 2. In the entanglement regime, the Z-dependence of ring viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1 < Z < 20, η0,linear/η0,ring ∼ Z 1.2±0.3, is weaker than the scaling prediction (η0,linear/η0,ring ∼ Z 1.6±0.3) and the simulations (η0,linear/ η0,ring ∼ Z2.0±0.3). Nevertheless, the present collection of state-of-the-art experimental data unambiguously demonstrates that rings exhibit a universal trend clearly departing from that of their linear counterparts, and hence it represents a major step toward resolving a 30-year-old problem. © 2013 American Chemical Society.

  6. Dynamics of Melting and Melt Migration as Inferred from Incompatible Trace Element Abundance in Abyssal Peridotites

    Science.gov (United States)

    Peng, Q.; Liang, Y.

    2008-12-01

    To better understand the melting processes beneath the mid-ocean ridge, we developed a simple model for trace element fractionation during concurrent melting and melt migration in an upwelling steady-state mantle column. Based on petrologic considerations, we divided the upwelling mantle into two regions: a double- lithology upper region where high permeability dunite channels are embedded in a lherzolite/harzburgite matrix, and a single-lithology lower region that consists of partially molten lherzolite. Melt generated in the single lithology region migrates upward through grain-scale diffuse porous flow, whereas melt in the lherzolite/harzburgite matrix in the double-lithology region is allowed to flow both vertically through the overlying matrix and horizontally into its neighboring dunite channels. There are three key dynamic parameters in our model: degree of melting experienced by the single lithology column (Fd), degree of melting experienced by the double lithology column (F), and a dimensionless melt suction rate (R) that measures the accumulated rate of melt extraction from the matrix to the channel relative to the accumulated rate of matrix melting. In terms of trace element fractionation, upwelling and melting in the single lithology column is equivalent to non-modal batch melting (R = 0), whereas melting and melt migration in the double lithology region is equivalent to a nonlinear combination of non-modal batch and fractional melting (0 abyssal peridotite, we showed, with the help of Monte Carlo simulations, that it is difficult to invert for all three dynamic parameters from a set of incompatible trace element data with confidence. However, given Fd, it is quite possible to constrain F and R from incompatible trace element abundances in residual peridotite. As an illustrative example, we used the simple melting model developed in this study and selected REE and Y abundance in diopside from abyssal peridotites to infer their melting and melt migration

  7. Molecular mechanism of melting of a helical polymer crystal: Role of conformational order, packing and mobility of polymers

    Science.gov (United States)

    Cheerla, Ramesh; Krishnan, Marimuthu

    2018-03-01

    The molecular mechanism of melting of a superheated helical polymer crystal has been investigated using isothermal-isobaric molecular dynamics simulation that allows anisotropic deformation of the crystal lattice. A detailed microscopic analysis of the onset and progression of melting and accompanying changes in the polymer conformational order, translational, and orientation order of the solid along the melting pathway is presented. Upon gradual heating from room temperature to beyond the melting point at ambient pressure, the crystal exhibits signatures of premelting well below the solid-to-liquid melting transition at the melting point. The melting transition is manifested by abrupt changes in the crystal volume, lattice energy, polymer conformation, and dynamical properties. In the premelting stage, the crystal lattice structure and backbone orientation of the polymer chains are retained but with the onset of weakening of long-range helical order and interchain packing of polymers perpendicular to the fibre axis of the crystal. The premelting also marks the onset of conformational defects and anisotropic solid-state diffusion of polymers along the fibre axis. The present study underscores the importance of the interplay between intermolecular packing, interactions, and conformational dynamics at the atomic level in determining the macroscopic melting behavior of polymer crystals.

  8. Photogeologic analysis of impact melt-rich lithologies in Kepler crater that could be sampled by future missions

    Science.gov (United States)

    Öhman, Teemu; Kring, David A.

    2012-02-01

    Kepler is a 31 km diameter Copernican age complex impact crater located on the nearside maria of the Moon. We used Lunar Reconnaissance Orbiter imagery and topographic data in combination with Kaguya terrain camera and other image data sets to construct a new geomorphologic sketch map of the Kepler crater, with a focus on impact melt-rich lithologies. Most of the interior melt rocks are preserved in smooth and hummocky floor materials. Smaller volumes of impact melt were deposited in rim veneer, interior and exterior ponds, and lobe-like overlapping flows on the upper crater wall. Based on shadow lengths, typical flows of melt-rich material on crater walls and the western rim flank are ˜1-5 m thick, and have yield strengths of ˜1-10 kPa. The melt rock distribution is notably asymmetric, with interior and exterior melt-rich deposits concentrated north and west of the crater center. This melt distribution and the similarly asymmetric ray distribution imply a slightly less than 45° impact trajectory from the southeast. The exposed wall of Kepler displays distinct layering, with individual layers having typical thicknesses of ˜3-5 m. These are interpreted as flows of Procellarum mare basalts in the impact target. From the point of view of exploration, numerous fractures and pits in the melt-rich floor materials not only enable detailed studies of melt-related processes of impact crater formation, but also provide potential shelters for longer duration manned lunar missions.

  9. Fundamental Aspects of Selective Melting Additive Manufacturing Processes

    Energy Technology Data Exchange (ETDEWEB)

    van Swol, Frank B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Miller, James E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-12-01

    Certain details of the additive manufacturing process known as selective laser melting (SLM) affect the performance of the final metal part. To unleash the full potential of SLM it is crucial that the process engineer in the field receives guidance about how to select values for a multitude of process variables employed in the building process. These include, for example, the type of powder (e.g., size distribution, shape, type of alloy), orientation of the build axis, the beam scan rate, the beam power density, the scan pattern and scan rate. The science-based selection of these settings con- stitutes an intrinsically challenging multi-physics problem involving heating and melting a metal alloy, reactive, dynamic wetting followed by re-solidification. In addition, inherent to the process is its considerable variability that stems from the powder packing. Each time a limited number of powder particles are placed, the stacking is intrinsically different from the previous, possessing a different geometry, and having a different set of contact areas with the surrounding particles. As a result, even if all other process parameters (scan rate, etc) are exactly the same, the shape and contact geometry and area of the final melt pool will be unique to that particular configuration. This report identifies the most important issues facing SLM, discusses the fundamental physics associated with it and points out how modeling can support the additive manufacturing efforts.

  10. Melting of 2D monatomic solids: Lennard-Jones system

    International Nuclear Information System (INIS)

    Yi, Y.M.; Guo, Z.C.

    1987-09-01

    The Lennard-Jones interaction has been introduced into the Collins mix lattice of 2D liquids. By means of rigorous calculation of the total potential and the free area, the Gibbs functions for 2D liquid and solid have been derived. The melting line obtained from the phase transition equation agrees quite well with the result of recent computer simulation experiments. The obtained reduced temperature of the triple point T* t =0.438 agrees with the data measured in experiments of some inert gas monolayers adsorbed on graphite as well as in computer simulation experiments. (author). 11 refs, 7 figs, 3 tabs

  11. Melt processed high-temperature superconductors

    CERN Document Server

    1993-01-01

    The achievement of large critical currents is critical to the applications of high-temperature superconductors. Recent developments have shown that melt processing is suitable for producing high J c oxide superconductors. Using magnetic forces between such high J c oxide superconductors and magnets, a person could be levitated.This book has grown largely out of research works on melt processing of high-temperature superconductors conducted at ISTEC Superconductivity Research Laboratory. The chapters build on melt processing, microstructural characterization, fundamentals of flux pinning, criti

  12. Bayesian estimation of core-melt probability

    International Nuclear Information System (INIS)

    Lewis, H.W.

    1984-01-01

    A very simple application of the canonical Bayesian algorithm is made to the problem of estimation of the probability of core melt in a commercial power reactor. An approximation to the results of the Rasmussen study on reactor safety is used as the prior distribution, and the observation that there has been no core melt yet is used as the single experiment. The result is a substantial decrease in the mean probability of core melt--factors of 2 to 4 for reasonable choices of parameters. The purpose is to illustrate the procedure, not to argue for the decrease

  13. Corium melt researches at VESTA test facility

    OpenAIRE

    Hwan Yeol Kim; Sang Mo An; Jaehoon Jung; Kwang Soon Ha; Jin Ho Song

    2017-01-01

    VESTA (Verification of Ex-vessel corium STAbilization) and VESTA-S (-small) test facilities were constructed at the Korea Atomic Energy Research Institute in 2010 to perform various corium melt experiments. Since then, several tests have been performed for the verification of an ex-vessel core catcher design for the EU-APR1400. Ablation tests of an impinging ZrO2 melt jet on a sacrificial material were performed to investigate the ablation characteristics. ZrO2 melt in an amount of 65–70 kg w...

  14. Corium melt researches at VESTA test facility

    Directory of Open Access Journals (Sweden)

    Hwan Yeol Kim

    2017-10-01

    Full Text Available VESTA (Verification of Ex-vessel corium STAbilization and VESTA-S (-small test facilities were constructed at the Korea Atomic Energy Research Institute in 2010 to perform various corium melt experiments. Since then, several tests have been performed for the verification of an ex-vessel core catcher design for the EU-APR1400. Ablation tests of an impinging ZrO2 melt jet on a sacrificial material were performed to investigate the ablation characteristics. ZrO2 melt in an amount of 65–70 kg was discharged onto a sacrificial material through a well-designed nozzle, after which the ablation depths were measured. Interaction tests between the metallic melt and sacrificial material were performed to investigate the interaction kinetics of the sacrificial material. Two types of melt were used: one is a metallic corium melt with Fe 46%, U 31%, Zr 16%, and Cr 7% (maximum possible content of U and Zr for C-40, and the other is a stainless steel (SUS304 melt. Metallic melt in an amount of 1.5–2.0 kg was delivered onto the sacrificial material, and the ablation depths were measured. Penetration tube failure tests were performed for an APR1400 equipped with 61 in-core instrumentation penetration nozzles and extended tubes at the reactor lower vessel. ZrO2 melt was generated in a melting crucible and delivered down into an interaction crucible where the test specimen is installed. To evaluate the tube ejection mechanism, temperature distributions of the reactor bottom head and in-core instrumentation penetration were measured by a series of thermocouples embedded along the specimen. In addition, lower vessel failure tests for the Fukushima Daiichi nuclear power plant are being performed. As a first step, the configuration of the molten core in the plant was investigated by a melting and solidification experiment. Approximately 5 kg of a mixture, whose composition in terms of weight is UO2 60%, Zr 10%, ZrO2 15%, SUS304 14%, and B4C 1%, was melted in a

  15. Shear melting and high temperature embrittlement: theory and application to machining titanium.

    Science.gov (United States)

    Healy, Con; Koch, Sascha; Siemers, Carsten; Mukherji, Debashis; Ackland, Graeme J

    2015-04-24

    We describe a dynamical phase transition occurring within a shear band at high temperature and under extremely high shear rates. With increasing temperature, dislocation deformation and grain boundary sliding are supplanted by amorphization in a highly localized nanoscale band, which allows for massive strain and fracture. The mechanism is similar to shear melting and leads to liquid metal embrittlement at high temperature. From simulation, we find that the necessary conditions are lack of dislocation slip systems, low thermal conduction, and temperature near the melting point. The first two are exhibited by bcc titanium alloys, and we show that the final one can be achieved experimentally by adding low-melting-point elements: specifically, we use insoluble rare earth metals (REMs). Under high shear, the REM becomes mixed with the titanium, lowering the melting point within the shear band and triggering the shear-melting transition. This in turn generates heat which remains localized in the shear band due to poor heat conduction. The material fractures along the shear band. We show how to utilize this transition in the creation of new titanium-based alloys with improved machinability.

  16. Decompression Melting beneath the Indonesian Volcanic Front

    Science.gov (United States)

    Kelley, K. A.; Colabella, A.; Sisson, T. W.; Hauri, E. H.; Sigurdsson, H.

    2006-12-01

    Subduction zone magmas are typically characterized by high concentrations of dissolved H2O (up to 6-7 wt%), presumably derived from the subducted plate and ultimately responsible for melt generation in this tectonic setting. Pressure-release melting from upward mantle flow, however, is increasingly cited as a secondary driver of mantle wedge melting. Here we report new SIMS volatile and LA-ICP-MS trace element data for olivine-hosted melt inclusions from Galunggung (GG) and Tambora (TB) volcanoes in the Indonesian subduction zone to evaluate the relative importance of decompression vs. H2O-flux melting beneath arc volcanoes. Prior studies of melt inclusions from Galunggung showed unusually low primary H2O concentrations (~0.5 wt%), implicating decompression as a significant mechanism of mantle melting beneath this volcano (Sisson &Bronto, 1998). Our new data from a larger suite of Galunggung melt inclusions show a bimodal distribution of H2O concentrations: a dominant population with ~0.5 wt% H2O, and a small group with 1.5-2.5 wt% H2O, indicating that a small amount of H2O addition from the slab may also contribute to mantle melting here. New volatile data from Tambora melt inclusions also indicate low primary H2O contents (1-2 wt%), suggesting that decompression melting may be a large-scale characteristic of the Indonesian volcanic front. Our new trace element data show both volcanoes are LREE enriched relative to MORB, but Tambora melts show greater LREE enrichment (La/Sm=1.7-2.7[GG]; 6.0- 9.5[TB]). Galunggung melts have Nb/Y in the range of NMORB (0.1-0.2), whereas Tambora Nb/Y is similar to EMORB (0.3-0.5). Most Tambora melt inclusions also have H2O/Y (Y (200-1000) and H2O/Ce (100-1400) relative to NMORB, suggesting a larger influence from slab-derived H2O despite having lower average H2O concentrations than Tambora. The range of H2O/Y and H2O/Ce at Galunggung, however, is largely within the range of back-arc basin basalts and does not preclude a major

  17. Evidence of melting, melt percolation and deformation in a supra-subduction zone (Marum ophiolite complex - Papua New Guinea)

    Science.gov (United States)

    Kaczmarek, M. A.; Jonda, L.; Davies, H. L.

    2015-12-01

    New geochemical and microstructural data from the Marum ophiolite in Papua New Guinea describe a piece of most depleted mantle made essentially of dunite and harzburgite showing compositions of supra-subduction zone (SSZ) peridotite. Strong olivine crystallographic preferred orientations (CPO) in dunite and harzburgite inferred the activation of both (001)[100] and (010)[100] slip systems. Clinopyroxene and orthopyroxene CPOs inferred the activation of (100)[001] and (010)[001] slip systems. This plastic deformation is interpreted to have developed at high temperature during the formation of the Marum ophiolite, prior to melt percolation. The orientation of the foliation and olivine [100] slip directions sub-parallel to the subduction zone indicates that mantle flow was parallel to the trench pointing a fast polarization direction parallel to the arc. Marum depleted mantle has been fertilised by diffuse crystallisation of a low proportion of clinopyroxene (1-2%) in the dunite and formation of cm-scale ol-clinopyroxenite and ol-websterite veins cross-cutting the foliation. This percolating melt shows silica-rich magnesian affinities (boninite-like) related to supra-subduction zone in a young fore-arc environment. The peridotite has also been percolated by a melt with more tholeiite affinities precipitating plagioclase-rich wehrlite and thin gabbroic veins; these are interpreted to form after the boninitic event. The small proportion of newly crystallized pyroxene distributed in the dunite shows similar orientation of crystallographic axes to the host dunite (ol parallel to cpx-opx). In contrast, the pyroxenes in ol-clinopyroxenite, ol-websterite and the thin gabbroic veins in the wehrlite, record their own orientation with axes at 45 to 60˚ to olivine axes. For low melt proportion, such as crystallization of pyroxenes in the dunite, the crystallization is governed by epitaxial growth, and when the proportion of melt is higher the newly formed minerals record syn

  18. Microstructures and microhardness evolutions of melt-spun Al-8Ni-5Nd-4Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Karakoese, Ercan, E-mail: ekarakose@karatekin.edu.tr [Karatekin University, Faculty of Sciences, Department of Physics, 18100 Cank Latin-Small-Letter-Dotless-I r Latin-Small-Letter-Dotless-I (Turkey); Keskin, Mustafa [Erciyes University, Faculty of Sciences, Department of Physics, 38039 Kayseri (Turkey)

    2012-03-15

    Al-Ni-Nd-Si alloy with nominal composition of Al-8 wt.%Ni-5 wt.%Nd-4 wt.%Si was rapidly solidified by using melt-spinning technique to examine the influence of the cooling rate/conditions on microstructure and mechanical properties. The resulting conventional cast (ingot) and melt-spun ribbons were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy together with energy dispersive spectroscopy, differential scanning calorimetry, differential thermal analysis and Vickers microhardness tester. The ingot alloys consists of four phases namely {alpha}-Al, intermetallic Al{sub 3}Ni, Al{sub 11}Nd{sub 3} and fcc Si. Melt-spun ribbons are completely composed of {alpha}-Al phase. The optical microscopy and scanning electron microscopy results show that the microstructures of rapidly solidified ribbons are clearly different from their ingot alloy. The change in microhardness is discussed based on the microstructural observations. - Highlights: Black-Right-Pointing-Pointer Rapid solidification allows a reduction in grain size, extended solid solution ranges. Black-Right-Pointing-Pointer We observed the matrix lattice parameter increases with increasing wheel speed. Black-Right-Pointing-Pointer Melt-spun ribbons consist of partly amorphous phases embedded in crystalline phases. Black-Right-Pointing-Pointer The solidification rate is high enough to retain most of alloying elements in the Al matrix. Black-Right-Pointing-Pointer The rapid solidification has effect on the phase constitution.

  19. Hypertension and hyperglycemia synergize to cause incipient renal tubular alterations resulting in increased NGAL urinary excretion in rats.

    Directory of Open Access Journals (Sweden)

    Ana M Blázquez-Medela

    Full Text Available Hypertension and diabetes are the two leading causes of chronic kidney disease (CKD eventually leading to end stage renal disease (ESRD and the need of renal replacement therapy. Mortality among CKD and ESRD patients is high, mostly due to cardiovascular events. New early markers of risk are necessary to better anticipate the course of the disease, to detect the renal affection of additive risk factors, and to appropriately handle patients in a pre-emptive and personalized manner.Renal function and NGAL urinary excretion was monitored in rats with spontaneous (SHR or L-NAME induced hypertension rendered hyperglycemic (or not as controls.Combination of hypertension and hyperglycemia (but not each of these factors independently causes an increased urinary excretion of neutrophil gelatinase-associated lipocalin (NGAL in the rat, in the absence of signs of renal damage. Increased NGAL excretion is observed in diabetic animals with two independent models of hypertension. Elevated urinary NGAL results from a specific alteration in its tubular handling, rather than from an increase in its renal expression. In fact, when kidneys of hyperglycaemic-hypertensive rats are perfused in situ with Krebs-dextran solution containing exogenous NGAL, they excrete more NGAL in the urine than hypertensive rats. We also show that albuminuria is not capable of detecting the additive effect posed by the coexistence of these two risk factors.Our results suggest that accumulation of hypertension and hyperglycemia induces an incipient and quite specific alteration in the tubular handling of NGAL resulting in its increased urinary excretion.

  20. In situ measurement of soil moisture and pore-water pressures in an 'incipient' landslide: Lake Tutira, New Zealand.

    Science.gov (United States)

    Hawke, Richard; McConchie, Jack

    2011-02-01

    The immediate cost of shallow regolith landslides in New Zealand has been estimated to exceed US$33M annually. Since the majority of these landslides occur during prolonged wet conditions, or intense rainstorms, moisture conditions are a critical control. The nature, dynamics, and character of soil moisture conditions, and the piezometric response to rainfall, have been recorded within an 'incipient' landslide for more than 5 years. The study site, on pastoral hill country within the Lake Tutira catchment in northern Hawkes Bay, is typical of large areas of New Zealand episodically affected by extensive landsliding. Detailed continuous measurements show that both the soil moisture and piezometric response within the regolith are highly storm- and site-specific. The development of positive pore pressures is infrequent; they form only during intense rainstorms, and persist for a short time. The hydraulic response of the soil is primarily a function of storm characteristics, but this response can be modified by antecedent moisture conditions, topographic position, and heterogeneity of soil properties. Stability analysis shows that most slopes in the study area are significantly steeper than can be explained by the frictional strength of the regolith. Measured hydraulic conditions also show that positive pore-water pressures alone do not trigger slope instability. A recent slope failure followed a period of extremely high antecedent moisture conditions, and occurred when maximum soil moisture conditions, though not pore-water pressures, were recorded. Increased moisture content of the regolith reduces matric tension, and therefore effective cohesion of the soil. This cohesion is critical to maintaining stability of the regolith on these slopes. Copyright © 2009 Elsevier Ltd. All rights reserved.

  1. Fault Growth and Propagation and its Effect on Surficial Processes within the Incipient Okavango Rift Zone, Northwest Botswana, Africa (Invited)

    Science.gov (United States)

    Atekwana, E. A.

    2010-12-01

    The Okavango Rift Zone (ORZ) is suggested to be a zone of incipient continental rifting occuring at the distal end of the southwestern branch of the East African Rift System (EARS), therefore providing a unique opportunity to investigate neotectonic processes during the early stages of rifting. We used geophysical (aeromagnetic, magnetotelluric), Shuttle Radar Tomography Mission, Digital Elevation Model (SRTM-DEM), and sedimentological data to characterize the growth and propagation of faults associated with continental extension in the ORZ, and to elucidate the interplay between neotectonics and surficial processes. The results suggest that: (1) fault growth occurs by along axis linkage of fault segments, (2) an immature border fault is developing through the process of “Fault Piracy” by fault-linkages between major fault systems, (3) significant discrepancies exits between the height of fault scarps and the throws across the faults compared to their lengths in the basement, (4) utilization of preexisting zones of weakness allowed the development of very long faults (> 25-100 km) at a very early stage of continental rifting, explaining the apparent paradox between the fault length versus throw for this young rift, (5) active faults are characterized by conductive anomalies resulting from fluids, whereas, inactive faults show no conductivity anomaly; and 6) sedimentlogical data reveal a major perturbation in lake sedimentation between 41 ka and 27 ka. The sedimentation perturbation is attributed to faulting associated with the rifting and may have resulted in the alteration of hydrology forming the modern day Okavango delta. We infer that this time period may represent the age of the latest rift reactivation and fault growth and propagation within the ORZ.

  2. Incipient Domestication Processes in Multicultural Contexts: A Case Study of Urban Parks in San Carlos de Bariloche (Argentina

    Directory of Open Access Journals (Sweden)

    Romina Betancurt

    2017-12-01

    urban parks are constructed cultural niches which, as in an agroforestry system, are scenarios which reveal processes of incipient domestication that reflect different cosmovisions and drivers typical of multicultural contexts.

  3. An underdamped stochastic resonance method with stable-state matching for incipient fault diagnosis of rolling element bearings

    Science.gov (United States)

    Lei, Yaguo; Qiao, Zijian; Xu, Xuefang; Lin, Jing; Niu, Shantao

    2017-09-01

    Most traditional overdamped monostable, bistable and even tristable stochastic resonance (SR) methods have three shortcomings in weak characteristic extraction: (1) their potential structures characterized by single stable-state type are insufficient to match with the complicated and diverse mechanical vibration signals; (2) they vulnerably suffer the interference from multiscale noise and largely depend on the help of highpass filters whose parameters are selected subjectively, probably resulting in false detection; and (3) their rescaling factors are fixed as constants generally, thereby ignoring the synergistic effect among vibration signals, potential structures and rescaling factors. These three shortcomings have limited the enhancement ability of SR. To explore the SR potential, this paper initially investigates the SR in a multistable system by calculating its output spectral amplification, further analyzes its output frequency response numerically, then examines the effect of both damping and rescaling factors on output responses and finally presents a promising underdamped SR method with stable-state matching for incipient bearing fault diagnosis. This method has three advantages: (1) the diversity of stable-state types in a multistable potential makes it easy to match with various vibration signals; (2) the underdamped multistable SR, equivalent to a moving nonlinear bandpass filter that is dependent on the rescaling factors, is able to suppress the multiscale noise; and (3) the synergistic effect among vibration signals, potential structures and rescaling and damping factors is achieved using quantum genetic algorithms whose fitness functions are new weighted signal-to-noise ratio (WSNR) instead of SNR. Therefore, the proposed method is expected to possess good enhancement ability. Simulated and experimental data of rolling element bearings demonstrate its effectiveness. The comparison results show that the proposed method is able to obtain higher

  4. Pattern of genetic differentiation of an incipient speciation process: The case of the high Andean killifish Orestias.

    Science.gov (United States)

    Guerrero-Jiménez, Claudia Jimena; Peña, Fabiola; Morales, Pamela; Méndez, Marco; Sallaberry, Michel; Vila, Irma; Poulin, Elie

    2017-01-01

    During the Pleistocene and Holocene, the southwest Andean Altiplano (17°-22°S) was affected by repeated fluctuations in water levels, high volcanic activity and major tectonic movements. In the early Holocene the humid Tauca phase shifted to the arid conditions that have lasted until the present, producing endorheic rivers, lakes, lagoons and wetlands. The endemic fish Orestias (Cyprinodontidae) represents a good model to observe the genetic differentiation that characterizes an incipient speciation process in allopatry since the morphospecies described inhabit a restricted geographic area, with present habitat fragmentation. The genetic diversity and population structure of four endemic morphospecies of Orestias (Cyprinodontidae) found in the Lauca National Park (LNP) analyzed with mitochondrial markers (Control Region) and eight microsatellites, revealed the existence of genetic groups that matches the fragmentation of these systems. High values of genetic and phylogeographic differentiation indices were observed between Chungará Lake and Piacota lagoon. The group composed of the Lauca River, Copapujo and Chuviri wetlands sampling sites showed a clear signal of expansion, with a star-like haplotype network. Levels of genetic differentiation were lower than in Chungará and Piacota, suggesting that these localities would have differentiated after the bottlenecks linked to the collapse of Parinacota volcano. The Parinacota sample showed a population signal that differed from the other localities revealing greater genetic diversity and a disperse network, presenting haplotypes shared with other LNP localities. A mixing pattern of the different genetic groups was evident using the microsatellite markers. The chronology of the vicariance events in LNP may indicate that the partition process of the Orestias populations was gradual. Considering this, and in view of the genetic results, we may conclude that the morphospecies from LNP are populations in ongoing

  5. Thermal hydraulic conditions inducing incipient cracking in the 900 MWe unit 93 D reactor coolant pump shafts

    International Nuclear Information System (INIS)

    Bore, C.

    1995-01-01

    From 1987, 900 MWe plant operating feedback revealed cracking in the lower part of the reactor coolant pump shafts, beneath the thermal ring. Metallurgical examinations established that this was due to a thermal fatigue phenomenon known as thermal crazing, occurring after a large number of cycles. Analysis of thermal hydraulic conditions initiating the cracks does not allow exact quantification of the thermal load inducing cracking. Only qualitative analyses are thus possible, the first of which, undertaken by the pump manufacturer, Jeumont Industrie, showed that the cracks could not be due to the major transients (stop-start, injection cut-off), which were too few in number. Another explanation was then put forward: the thermal ring, shrunk onto the shaft it is required to protect against thermal shocks, loosens to allow an alternating downflow of cold water from the shaft seals and an upflow of hot water from the primary system. However, approximate calculations showed that the flow involved would be too slight to initiate the cracking observed. A more stringent analysis undertaken with the 2D flow analysis code MELODIE subsequently refuted the possibility of alternating flows beneath the ring establishing that only a hot water upflow occurred due to a 'viscosity pump' phenomenon. Crack initiation was finally considered to be due to flowrate variations beneath the ring, with the associated temperature fluctuations. This flowrate fluctuation could be due to an unidentified transient phenomenon or to a variation in pump operating conditions. This analysis of the hydraulic conditions initiating the cracks disregards shaft surface residual stresses. These are tensile stresses and show that loads less penalizing than those initially retained could cause incipient cracking. Thermal ring modifications to reduce these risks were proposed and implemented. In addition, final metallurgical treatment of the shafts was altered and implemented. In addition, final metallurgical

  6. Experimental-theoretical approach to carbon monoxide density calculation at the incipient stage of the fire indoors

    Science.gov (United States)

    Puzach, S. V.; Suleykin, E. V.; Akperov, R. G.; Nguyen, T. D.

    2017-11-01

    A new experimental-theoretical approach to the toxic gases concentrations assessment in case of fire indoors is offered. The analytical formulas for calculation of CO average volume density are received. These formulas do not contain the geometrical sizes of the room and surfaces dimensions of combustible materials and, therefore, are valid under conditions of as a small-scale fire as a large-scale fire. A small-scale experimental installation for modeling fire thermal and gas dynamics in the closed or open thermodynamic system has been designed. The results of the experiments on determining dependencies of CO average volume density from average volume temperature and oxygen average volume density as well as dependencies of specific coefficients of CO emission and specific mass rates of the combustible material gasification from the time of tests during the burning of wood, transformer oil and PVC cables shield are presented. The results of numerical experiments on CO density calculation in small and large scale rooms using the proposed analytical solutions, integral, zone and field models for calculation of fire thermal and gas dynamics are presented. The comparison with the experimental data obtained by the authors and given in the literature has been performed. It is shown that CO density calculation in the full-scale room at the incipient stage of the fire can be carried out taking into account only the experimental dependences of CO from temperature or O2 density, that have been obtained from small-scale experiments. Therefore the solution of the equation of carbon monoxide mass conservation law is not necessary.

  7. Comparison between RVG UI sensor and Kodak InSight film for detection of incipient proximal caries

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Yukiko; Hanazawa, Tomomi; Seki, Kenji; Araki, Kazuyuki; Okano, Tomohiro [Showa Univ., Tokyo (Japan). School of Dentistry

    2002-12-01

    The purpose of this study was to compare the efficacy of the four combination modes of Trophy Radio Visio Graphy (RVG) UI sensor (Trex-Trophy Radiology Inc., Marne-la-Valee, France) and Kodak InSight film (Eastman Kodak Co., Rochester, NY) for detecting proximal dental caries. Thirty extracted human upper premolars were selected. Of 60 surfaces, 25 had carious lesions in the form of small cavities, and the rest showed no evidence of caries as verified by a micro computed tomogram (micro CT; XCT Research SA+, Stratec Medizintechnik GmbH, Pforzheim, Germany). All teeth were radiographed with the paralleling technique (60 kV, 40 cm focus-to-sensor distance). Four combination modes (high-resolution caries mode-HRC; high-sensitivity caries mode-HSC; high-resolution periodontal mode-HRP; and high-resolution endo mode-HRE) were used. Exposure was set at 0.12 sec for HRC, 0.08 sec for HSC, 0.16 sec for HRP, 0.12 sec for HRE, and 0.16 sec for the Kodak InSight film. The resulting images were evaluated by three oral radiologists. The same three observers evaluated the digital images, and were allowed to use the contrast and brightness controls in doing so. Possible differences in receiver operating characteristic (ROC) curve areas among image modalities were assessed by the Friedman test. The mean ROC curve areas were 0.66{+-}0.11 for HRC, 0.78{+-}0.02 for HSC, 0.76{+-}0.04 for HRE, 0.77{+-}0.04 for HRP, and 0.71{+-}0.09 for the Kodak InSight film. There were no statistically significant differences between HRC, HSC, HRE, HRP and the Kodak InSight film in terms of proximal caries detection. The four modes of RVG UI system are each a viable alternative to intraoral film for the detection of incipient dental caries. (author)

  8. Pattern of genetic differentiation of an incipient speciation process: The case of the high Andean killifish Orestias

    Science.gov (United States)

    Guerrero-Jiménez, Claudia Jimena; Peña, Fabiola; Morales, Pamela; Méndez, Marco; Sallaberry, Michel; Vila, Irma; Poulin, Elie

    2017-01-01

    During the Pleistocene and Holocene, the southwest Andean Altiplano (17°-22°S) was affected by repeated fluctuations in water levels, high volcanic activity and major tectonic movements. In the early Holocene the humid Tauca phase shifted to the arid conditions that have lasted until the present, producing endorheic rivers, lakes, lagoons and wetlands. The endemic fish Orestias (Cyprinodontidae) represents a good model to observe the genetic differentiation that characterizes an incipient speciation process in allopatry since the morphospecies described inhabit a restricted geographic area, with present habitat fragmentation. The genetic diversity and population structure of four endemic morphospecies of Orestias (Cyprinodontidae) found in the Lauca National Park (LNP) analyzed with mitochondrial markers (Control Region) and eight microsatellites, revealed the existence of genetic groups that matches the fragmentation of these systems. High values of genetic and phylogeographic differentiation indices were observed between Chungará Lake and Piacota lagoon. The group composed of the Lauca River, Copapujo and Chuviri wetlands sampling sites showed a clear signal of expansion, with a star-like haplotype network. Levels of genetic differentiation were lower than in Chungará and Piacota, suggesting that these localities would have differentiated after the bottlenecks linked to the collapse of Parinacota volcano. The Parinacota sample showed a population signal that differed from the other localities revealing greater genetic diversity and a disperse network, presenting haplotypes shared with other LNP localities. A mixing pattern of the different genetic groups was evident using the microsatellite markers. The chronology of the vicariance events in LNP may indicate that the partition process of the Orestias populations was gradual. Considering this, and in view of the genetic results, we may conclude that the morphospecies from LNP are populations in ongoing

  9. Entre signo e significante: a esquizofrenia incipiente segundo Conrad Between sign and signifier: the incipient schizophrenia according to Conrad

    Directory of Open Access Journals (Sweden)

    Antônio Teixeira

    2006-06-01

    Full Text Available Ao tratar da pesquisa empreendida por J. Conrad sobre a esquizofrenia incipiente, esse artigo demonstra a atualidade desse estudo: destaca-se a abordagem estrutural do desencadeamento psicótico ali inaugurada antes mesmo de Lacan estender a perspectiva estruturalista à fenomenologia da clínica. Enfatiza-se a estratégia utilizada por Conrad, que propõe pensar o desencadeamento psicótico nos termos da estrutura formal da percepção delirante. Demonstra-se em que sentido a perspectiva de Conrad resgata a inteligibilidade do fenômeno psicótico, opondo-se à estratégia da fenomenologia compreensiva fundada por Jaspers, a qual relegava ao plano somático da causalidade física os fenômenos mentais destituídos de compreensão.By dealing with Conrad's research on incipient schizophrenia, this article demonstrates the actual relevance of the study: it highlights the structural approach of psychotic crisis inaugurated by him, even before Lacan expands the structuralist perspective to the clinic's phenomenology. The author emphasizes the strategy employed by Conrad, who proposes to discuss the origins of psychotic crisis in terms of the formal structure of the delirious perception. He shows therefore the way Conrad's perspective is able to recover the intelligibility of the psychotic phenomenon, in opposition to the strategy of comprehensive phenomenology founded by Jaspers, which relegates to the somatic plan of physical causality the mental occurrences deprived of comprehension.

  10. Electron beam melting of bearing materials

    Energy Technology Data Exchange (ETDEWEB)

    Goldschmied, G.; Schuler, A. (Technische Univ., Vienna (Austria). Inst. fuer Allgemeine Elektrotechnik); Elsinger, G.; Koroschetz, F. (MIBA Gleitlager AG, Laakirchen (Austria)); Tschegg, E.K. (Technische Univ., Vienna (Austria). Inst. fuer Angewandte und Technische Physik)

    1990-06-01

    This paper reports on a surface treatment method for the bearing materials AlSn6 which permits the use of this material without the overlay usually required. Microstructural refinement is achieved by means of a surface melting technique using an electron beam with successive rapid solidification. Extremely fine tin precipitates are formed in the melted surface layer which lead to significantly better tribological properties of the bearing material. Tests compared the tribological properties for AlSn6 bearings treated by the surface melting technique with those of untreated bearings. Whereas all untreated bearings failed by seizure after only 2 h of testing, 30% of the tested bearings which had been surface melted survived the entire testing program without damage.

  11. ESR melting under constant voltage conditions

    Energy Technology Data Exchange (ETDEWEB)

    Schlienger, M.E.

    1997-02-01

    Typical industrial ESR melting practice includes operation at a constant current. This constant current operation is achieved through the use of a power supply whose output provides this constant current characteristic. Analysis of this melting mode indicates that the ESR process under conditions of constant current is inherently unstable. Analysis also indicates that ESR melting under the condition of a constant applied voltage yields a process which is inherently stable. This paper reviews the process stability arguments for both constant current and constant voltage operation. Explanations are given as to why there is a difference between the two modes of operation. Finally, constant voltage process considerations such as melt rate control, response to electrode anomalies and impact on solidification will be discussed.

  12. Selective Laser Ablation and Melting, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — In this project Advratech will develop a new additive manufacturing (AM) process called Selective Laser Ablation and Melting (SLAM). The key innovation in this...

  13. Are Entangled Polymer Melts Different From Solutions?

    DEFF Research Database (Denmark)

    Huang, Qian; Mednova, Olga; Rasmussen, Henrik K.

    to further investigate the extensional steady state viscosity of polymer melts, we carefully synthesized two monodisperse polystyrenes with molar masses of 248 and 484 kg/mole. The start-up and steady uniaxial elongational viscosity have been measured for the two melts using a filament stretching rheometer....... We then compared the measurements with the bi-disperse polystyrene melts made from the above two polymers. The influence and sensitivity of impurities were studied by adding different percentages of 484k into 248k polystyrene melt. Furthermore a polydisperse polystyrene with weight average molecular...... weight 230 kg/mole was also measured for comparison. Possible reasons for the differences shown in the previously mentioned experiments are discussed....

  14. Melt Stirring by Horizontal Crucible Vibration

    Science.gov (United States)

    Wolf, M. F.; Elwell, D.; Feigelson, R. S.

    1985-01-01

    Horizontal vibration suggested as technique for more effective stirring of melts in crystal-growth apparatus. Vibrational technique may replace accelerated crucible rotation. Potential superiority of vibrational technique shown by preliminary experiments in which ink stirred into water.

  15. Energy Saving Melting and Revert Reduction Technology (E-SMARRT): Melting Efficiency Improvement

    Energy Technology Data Exchange (ETDEWEB)

    Principal Investigator Kent Peaslee; Co-PI’s: Von Richards, Jeffrey Smith

    2012-07-31

    Steel foundries melt recycled scrap in electric furnaces and typically consume 35-100% excess energy from the theoretical energy requirement required to pour metal castings. This excess melting energy is multiplied by yield losses during casting and finishing operations resulting in the embodied energy in a cast product typically being three to six times the theoretical energy requirement. The purpose of this research project was to study steel foundry melting operations to understand energy use and requirements for casting operations, define variations in energy consumption, determine technologies and practices that are successful in reducing melting energy and develop new melting techniques and tools to improve the energy efficiency of melting in steel foundry operations.

  16. Partial Melting of Lower Oceanic Crust Gabbro: Constraints From Poikilitic Clinopyroxene Primocrysts

    Directory of Open Access Journals (Sweden)

    Julien Leuthold

    2018-03-01

    Full Text Available Successive magma batches underplate, ascend, stall and erupt along spreading ridges, building the oceanic crust. It is therefore important to understand the processes and conditions under which magma differentiates at mid ocean ridges. Although fractional crystallization is considered to be the dominant mechanism for magma differentiation, open-system igneous complexes also experience Melting-Assimilation-Storage-Hybridization (MASH, Hildreth and Moorbath, 1988 processes. Here, we examine crystal-scale records of partial melting in lower crustal gabbroic cumulates from the slow-spreading Atlantic oceanic ridge (Kane Megamullion; collected with Jason ROV and the fast-spreading East Pacific Rise (Hess Deep; IODP expedition 345. Clinopyroxene oikocrysts in these gabbros preserve marked intra-crystal geochemical variations that point to crystallization-dissolution episodes in the gabbro eutectic assemblage. Kane Megamullion and Hess Deep clinopyroxene core1 primocrysts and their plagioclase inclusions indicate crystallization from high temperature basalt (>1,160 and >1,200°C, respectively, close to clinopyroxene saturation temperature (<50% and <25% crystallization. Step-like compatible Cr (and co-varying Al and incompatible Ti, Zr, Y and rare earth elements (REE decrease from anhedral core1 to overgrown core2, while Mg# and Sr/Sr* ratios increase. We show that partial resorption textures and geochemical zoning result from partial melting of REE-poor lower oceanic crust gabbroic cumulate (protolith following intrusion by hot primitive mantle-derived melt, and subsequent overgrowth crystallization (refertilization from a hybrid melt. In addition, toward the outer rims of crystals, Ti, Zr, Y and the REE strongly increase and Al, Cr, Mg#, Eu/Eu*, and Sr/Sr* decrease, suggesting crystallization either from late-stage percolating relatively differentiated melt or from in situ trapped melt. Intrusion of primitive hot reactive melt and percolation of

  17. DWPF Macrobatch 2 Melt Rate Tests

    Energy Technology Data Exchange (ETDEWEB)

    Stone, M.E.

    2001-01-03

    The Defense Waste Processing Facility (DWPF) canister production rate must be increased to meet canister production goals. Although a number of factors exist that could potentially increase melt rate, this study focused on two: (1) changes in frit composition and (2) changes to the feed preparation process to alter the redox of the melter feed. These two factors were investigated for Macrobatch 2 (sludge batch 1B) utilizing crucible studies and a specially designed ''melt rate'' furnace. Other potential factors that could increase melt rate include: mechanical mixing via stirring or the use of bubblers, changing the power skewing to redistribute the power input to the melter, and elimination of heat loss (e.g. air in leakage). The melt rate testing in FY00 demonstrated that melt rate can be improved by adding a different frit or producing a much more reducing glass by the addition of sugar as a reductant. The frit that melted the fastest in the melt rate testing was Frit 165. A paper stud y was performed using the Product Composition Control System (PCCS) to determine the impact on predicted glass viscosity, liquidus, durability, and operating window if the frit was changed from Frit 200 to Frit 165. PCCS indicated that the window was very similar for both frits. In addition, the predicted viscosity of the frit 165 glass was 46 poise versus 84 poise for the Frit 200 glass. As a result, a change from Frit 200 to Frit 165 is expected to increase the melt rate in DWPF without decreasing waste loading.

  18. Grain boundary disordering just before partial melting

    Science.gov (United States)

    Takei, Y.

    2017-12-01

    Recent experimental studies by using a rock analogue (organic polycrystals) have shown that significant enhancement of anelastic relaxation and steady-state creep in the partially molten aggregates starts from considerably below the solidus temperature in the absence of melt (Takei et al, 2014; Yamauchi & Takei, 2016, JGR). These results suggest that melt is not necessary to explain the seismic low velocity, high attenuation, and weak viscosity regions in the upper mantle. Indeed, Priestley & McKenzie (2006, 2013, EPSL) captured a steep reduction of seismic Vs just below the dry peridotite solidus, which was explained well by the empirical model of Yamauchi & Takei (2016). In spite of many geophysical implications (Takei, 2017, Ann. Rev. EPS, in press), however, underlying physics for the mechanical weakening just before partial melting remains unclear. The purpose of this study is to develop a physical model. Anelasticity and viscosity measured by Yamauchi & Takei (2016) are both rate-controlled by grain-boundary diffusion. Therefore, their observations suggest that the dynamic properties of grain boundary change just before partial melting. Significant disordering of grain boundary just before partial melting has been predicted theoretically in the area of material sciences (sometimes called `pre-melting'). I will summarize the thermodynamic models of grain boundary developed in these studies, and compare the predictions of these models to the experimental observations by Yamauchi & Takei (2016). Using these models, I will also clarify a relationship between grain-boundary disordering and grain-boundary wetting, and a different behavior between pure and binary systems in pre-melting. Acknowledgement: I thank R. Cooper for letting me know about the theoretical studies of pre-melting in binary eutectic system.

  19. Uniaxial Elongational viscosity of bidisperse polystyrene melts

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

    2006-01-01

    The startup and steady uniaxial elongational viscosity have been measured for three bidisperse polystyrene (PS) melts, consisting of blends of monodisperse PS with molecular weights of 52 kg/mole or 103 kg/mole and 390 kg/mole. The bidisperse melts have a maximum in the steady elongational...... viscosity, of up to a factor of 7 times the Trouton limit of 3 times the zero-shear viscosity....

  20. Electrodepositions on Tantalum in Alkali Halide Melts

    DEFF Research Database (Denmark)

    Barner, Jens H. Von; Jensen, Annemette Hindhede; Christensen, Erik

    2013-01-01

    Surface layers of tantalum metal were electrodeposited on steel from K2TaF7-LiF-NaF-KF melts. With careful control of the oxide contents dense and adherent deposits could be obtained by pulse plating. In NaCl-KCl-NaF-Na2CO3 and NaCl-KCl-Na2CO3 melts carbonate ions seems to be reduced to carbon in...

  1. Electrodepositions on Tantalum in alkali halide melts

    DEFF Research Database (Denmark)

    Barner, Jens H. Von; Jensen, Annemette Hindhede; Christensen, Erik

    2012-01-01

    Surface layers of tantalum metal were electrodeposited on steel from K 2TaF7-LiF-NaF-KF melts. With careful control of the oxide contents dense and adherent deposits could be obtained by pulse plating. In NaCl-KCl-NaF-Na2CO3 and NaCl-KCl-Na2CO 3 melts carbonate ions seems to be reduced to carbon ...

  2. Melt spreading code assessment, modifications, and application to the EPR core catcher design

    International Nuclear Information System (INIS)

    Farmer, M.T.

    2009-01-01

    of: (1) comparison to an analytical solution for the dam break problem, (2) water spreading tests in a 1/10 linear scale model of the Mark I containment by Theofanous et al., and (3) steel spreading tests by Suzuki et al. that were also conducted in a geometry similar to the Mark I. The objective of this work was to utilize the MELTSPREAD code to check the assumption of uniform melt spreading in the EPR core catcher design. As a starting point for the project, the code was validated against the worldwide melt spreading database that emerged after the code was originally written in the very early 1990's. As part of this exercise, the code was extensively modified and upgraded to incorporate findings from these various analytical and experiment programs. In terms of expanding the ability of the code to analyze various melt simulant experiments, the options to input user-specified melt and/or substrate material properties was added. The ability to perform invisicid and/or adiabatic spreading analysis was also added so that comparisons with analytical solutions and isothermal spreading tests could be carried out. In terms of refining the capability to carry out reactor material melt spreading analyses, the code was upgraded with a new melt viscosity model; the capability was added to treat situations in which solid fraction buildup between the liquidus-solidus is non-linear; and finally, the ability to treat an interfacial heat transfer resistance between the melt and substrate was incorporated. This last set of changes substantially improved the predictive capability of the code in terms of addressing reactor material melt spreading tests. Aside from improvements and upgrades, a method was developed to fit the model to the various melt spreading tests in a manner that allowed uncertainties in the model predictions to be statistically characterized. With these results, a sensitivity study was performed to investigate the assumption of uniform spreading in the EPR core

  3. Behavior of metals in ash melting and gasification-melting of municipal solid waste (MSW).

    Science.gov (United States)

    Jung, C H; Matsuto, T; Tanaka, N

    2005-01-01

    In this study, metal behavior in ash-melting and municipal solid waste (MSW) gasification-melting facilities were investigated. Eight ash-melting and three MSW gasification-melting facilities with a variety of melting processes and feedstocks were selected. From each facility, melting furnace fly ash (MFA) and molten slag were sampled, and feedstock of the ash-melting processes was also taken. For the ash melting process, the generation rate of MFA was well correlated with the ratio of incineration fly ash (IFA) in feedstock, and this was because MFA was formed mostly by mass transfer from IFA and a limited amount from bottom ash (BA). Distribution ratios of metal elements to MFA were generally determined by volatility of the metal element, but chlorine content in feedstock had a significant effect on Cu and a marginal effect on Pb. Distribution ratio of Zn to MFA was influenced by the oxidizing atmosphere in the furnace. High MFA generation and distribution ratio of non-volatile metals to MFA in gasification-melting facilities was probably caused by carry-over of fine particles to the air pollution control system due to large gas volume. Finally, dilution effect was shown to have a significant effect on metal concentration in MFA.

  4. Rapakivi texture formation via disequilibrium melting in a contact partial melt zone, Antarctica

    Science.gov (United States)

    Currier, R. M.

    2017-12-01

    In the McMurdo Dry Valleys of Antarctica, a Jurassic aged dolerite sill induced partial melting of granite in the shallow crust. The melt zone can be traced in full, from high degrees of melting (>60%) along the dolerite contact, to no apparent signs of melting, 10s of meters above the contact. Within this melt zone, the well-known rapakivi texture is found, arrested in various stages of development. High above the contact, and at low degrees of melting, K-feldspar crystals are slightly rounded and unmantled. In the lower half of the melt zone, mantles of cellular textured plagioclase appear on K-feldspar, and thicken towards the contact heat source. At the highest degrees of melting, cellular-textured plagioclase completely replaces restitic K-feldspar. Because of the complete exposure and intact context, the leading models of rapakivi texture formation can be tested against this system. The previously proposed mechanisms of subisothermal decompression, magma-mixing, and hydrothermal exsolution all fail to adequately describe rapakivi generation in this melt zone. Preferred here is a closed system model that invokes the production of a heterogeneous, disequilibrium melt through rapid heating, followed by calcium and sodium rich melt reacting in a peritectic fashion with restitic K-feldspar crystals. This peritectic reaction results in the production of plagioclase of andesine-oligoclase composition—which is consistent with not just mantles in the melt zone, but globally as well. The thickness of the mantle is diffusion limited, and thus a measure of the diffusive length scale of sodium and calcium over the time scale of melting. Thermal modeling provides a time scale of melting that is consistent with the thickness of observed mantles. Lastly, the distribution of mantled feldspars is highly ordered in this melt zone, but if it were mobilized and homogenized—mixing together cellular plagioclase, mantled feldspars, and unmantled feldspars—the result would be

  5. Fatigue behavior of porous biomaterials manufactured using selective laser melting.

    Science.gov (United States)

    Yavari, S Amin; Wauthle, R; van der Stok, J; Riemslag, A C; Janssen, M; Mulier, M; Kruth, J P; Schrooten, J; Weinans, H; Zadpoor, A A

    2013-12-01

    Porous titanium alloys are considered promising bone-mimicking biomaterials. Additive manufacturing techniques such as selective laser melting allow for manufacturing of porous titanium structures with a precise design of micro-architecture. The mechanical properties of selective laser melted porous titanium alloys with different designs of micro-architecture have been already studied and are shown to be in the range of mechanical properties of bone. However, the fatigue behavior of this biomaterial is not yet well understood. We studied the fatigue behavior of porous structures made of Ti6Al4V ELI powder using selective laser melting. Four different porous structures were manufactured with porosities between 68 and 84% and the fatigue S-N curves of these four porous structures were determined. The three-stage mechanism of fatigue failure of these porous structures is described and studied in detail. It was found that the absolute S-N curves of these four porous structures are very different. In general, given the same absolute stress level, the fatigue life is much shorter for more porous structures. However, the normalized fatigue S-N curves of these four structures were found to be very similar. A power law was fitted to all data points of the normalized S-N curves. It is shown that the measured data points conform to the fitted power law very well, R(2)=0.94. This power law may therefore help in estimating the fatigue life of porous structures for which no fatigue test data is available. It is also observed that the normalized endurance limit of all tested porous structures (<0.2) is lower than that of corresponding solid material (c.a. 0.4). © 2013.

  6. Experimental Investigation of Concrete Runway Snow Melting Utilizing Heat Pipe Technology

    Directory of Open Access Journals (Sweden)

    Fengchen Chen

    2018-01-01

    Full Text Available A full scale snow melting system with heat pipe technology is built in this work, which avoids the negative effects on concrete structure and environment caused by traditional deicing chemicals. The snow melting, ice-freezing performance and temperature distribution characteristics of heat pipe concrete runway were discussed by the outdoor experiments. The results show that the temperature of the concrete pavement is greatly improved with the heat pipe system. The environment temperature and embedded depth of heat pipe play a dominant role among the decision variables of the snow melting system. Heat pipe snow melting pavement melts the snow completely and avoids freezing at any time when the environment temperature is below freezing point, which is secure enough for planes take-off and landing. Besides, the exportation and recovery of geothermal energy indicate that this system can run for a long time. This paper will be useful for the design and application of the heat pipe used in the runway snow melting.

  7. A Novel Inorganic Low Melting Electrolyte for Secondary-Aluminum-Nickel Sulfide Batteries

    DEFF Research Database (Denmark)

    Hjuler, H.A.; Winbrush, S. von; Berg, Rolf W.

    1989-01-01

    A new, inorganic low melting electrolyte with the composition LiAlCl4-NaAlCl4-NaAlBr4-KAlCl4 (3:2:3:2) [or equivalentlyLiAlBr4-NaAlCl4-KAlCl4 (3:5:2)] has been developed. The melting point for this neutral melt is 86°C; the decompositionpotential is approximately 2.0V; the ionic conductivity...... is measured in the range 97°–401°C and is 0.142s cm–1 at100°C, and the density is 2.07g cm–3. The conductivity seems to be an almost linear combination of the conductivities ofthe four individual halo salts which form the melt. Other examined higher melting mixtures exhibit conductivities deviatingless than...... ±10% from their combination expectations. The low melting electrolyte is employed in the rechargeable batterysystem Al/electrolyte/Ni3S2 at 100°C. The open-circuit voltage of this system is from 0.82 to 1.0V. Dendrite-free aluminumdeposits are obtained. The cycling behavior of the battery system...

  8. Effect of disorder on the melting phase transition

    International Nuclear Information System (INIS)

    Storey, M.

    1999-01-01

    This Ph.D thesis is concerned with the effect of disorder on the melting phase transition. In the first part, the research is focused on the melting of the flux lines in high temperature superconductors. An analytical approach to studying the effect of quenched disorder on the vortices is proposed. The main steps in proposed approach are drawn from classical thermodynamics. The principal step is to relate a superconductor in the flux line lattice state to a closed system in which two phases are in contact, solid and liquid, with the aim of determining what effect the pinning centres have on the melting temperature. That is to determine whether the melting temperature is raised or lowered with respect to that of the clean non-pinned superconductor. Flux lines are modelled by an elastic Hamiltonian and the quenched disorder by the Larkin pinning Hamiltonian. This analyses is performed for two-dimensional systems as well as three-dimensional ones. The second part of this thesis is concerned with a simulation approach to analysing the melting transition in two-dimension. Joint Molecular Dynamics-Monte Carlo simulations are performed to study the melting transition in two dimensions. Firstly, classical point particles interacting via a r -12 repulsive pair potential are investigated and secondly, disorder is added to this system by introducing randomly positioned attractive pins. In both cases the simulation method chosen is based on the bicanonical ensemble in conjunction with constant temperature molecular dynamics as introduced by H.C. Andersen. Bond orientational order, transitional order, pressure, and the specific heat as well as the potential energy of the system are determined. Histograms of these quantities are obtained throughout the transition region and used together with finite size scaling analysis to deduce t lie nature of the transition by, means of the Lee-Kosterlitz method. For the clean system the r -12 potential is first studied and is chosen for its

  9. Point Defects in Hard Sphere Crystals

    OpenAIRE

    Pronk, Sander; Frenkel, Daan

    2001-01-01

    We report numerical calculations of the concentration of interstitials in hard-sphere crystals. We find that, in a three-dimensional fcc hard-sphere crystal at the melting point, the concentration of interstitials is 2 * 10^-8. This is some three orders of magnitude lower than the concentration of vacancies. A simple, analytical estimate yields a value that is in fair agreement with the numerical results.

  10. Wetting and surface tension of bismate glass melt

    International Nuclear Information System (INIS)

    Shim, Seung-Bo; Kim, Dong-Sun; Hwang, Seongjin; Kim, Hyungsun

    2009-01-01

    Lead oxide glass frits are used widely in the electronics industry for low-temperature firing. On the other hand, one of the low-sintering and low-melting lead-free glass systems available, the bismate glass system, is considered to be an alternative to lead oxide glass. In order to extend the applications of Bi 2 O 3 glasses, this study examined the thermophysical properties of low-melting Bi 2 O 3 -B 2 O 3 -ZnO-BaO-Al 2 O 3 -SiO 2 glass frits with various ZnO/B 2 O 3 ratios. The fundamental thermal properties, such as glass transition temperature and softening point, were examined by differential thermal analysis and a glass softening point determination system. The wetting angles, viscosities and surface tension of the various bismate glasses on an alumina substrate were measured using hot-stage microscopy and the sessile drop method. These thermophysical properties will be helpful in understanding the work of adhesion and the liquid spread kinetics of glass frits.

  11. Low melting high lithia glass compositions and methods

    Science.gov (United States)

    Jantzen, Carol M.; Pickett, John B.; Cicero-Herman, Connie A.; Marra, James C.

    2000-01-01

    The invention relates to methods of vitrifying waste and for lowering the melting point of glass forming systems by including lithia formers in the glass forming composition in significant amounts, typically from about 0.16 wt % to about 11 wt %, based on the total glass forming oxides. The lithia is typically included as a replacement for alkali oxide glass formers that would normally be present in a particular glass forming system. Replacement can occur on a mole percent or weight percent basis, and typically results in a composition wherein lithia forms about 10 wt % to about 100 wt % of the alkali oxide glass formers present in the composition. The present invention also relates to the high lithia glass compositions formed by these methods. The invention is useful for stabilization of numerous types of waste materials, including aqueous waste streams, sludge solids, mixtures of aqueous supernate and sludge solids, combinations of spent filter aids from waste water treatment and waste sludges, supernate alone, incinerator ash, incinerator offgas blowdown, or combinations thereof, geological mine tailings and sludges, asbestos, inorganic filter media, cement waste forms in need of remediation, spent or partially spent ion exchange resins or zeolites, contaminated soils, lead paint, etc. The decrease in melting point achieved by the present invention desirably prevents volatilization of hazardous or radioactive species during vitrification.

  12. The role of albedo and accumulation in the 2010 melting record in Greenland

    NARCIS (Netherlands)

    Tedesco, M.; Fettweis, X.; van den Broeke, M.R.|info:eu-repo/dai/nl/073765643; van de Wal, R.S.W.|info:eu-repo/dai/nl/101899556; Smeets, C.J.P.P.|info:eu-repo/dai/nl/191522236; van de Berg, W.J.|info:eu-repo/dai/nl/304831611; Serreze, M.C.; Box, J.E.

    2011-01-01

    Analyses of remote sensing data, surface observations and output from a regional atmosphere model point to new records in 2010 for surface melt and albedo, runoff, the number of days when bare ice is exposed and surface mass balance of the Greenland ice sheet, especially over its west and southwest

  13. Final report for SERDP WP-2209 Replacement melt-castable formulations for Composition B

    Science.gov (United States)

    2017-05-19

    using Topspin© software. FTIR spectra were acquired on a Nicolet iQ system using Omnic© software. Melting point determination was accomplished using a...salts tend to absorb water. In the case of AAD this sorption was studied by ARDEC and determined to be an issue only above a relative humidity of 50

  14. Melting of size-selected gallium clusters with 60-183 atoms.

    Science.gov (United States)

    Pyfer, Katheryne L; Kafader, Jared O; Yalamanchali, Anirudh; Jarrold, Martin F

    2014-07-10

    Heat capacities have been measured as a function of temperature for size-selected gallium cluster cations with between 60 and 183 atoms. Almost all clusters studied show a single peak in the heat capacity that is attributed to a melting transition. The peaks can be fit by a two-state model incorporating only fully solid-like and fully liquid-like species, and hence no partially melted intermediates. The exceptions are Ga90(+), which does not show a peak, and Ga80(+) and Ga81(+), which show two peaks. For the clusters with two peaks, the lower temperature peak is attributed to a structural transition. The melting temperatures for clusters with less than 50 atoms have previously been shown to be hundreds of degrees above the bulk melting point. For clusters with more than 60 atoms the melting temperatures decrease, approaching the bulk value (303 K) at around 95 atoms, and then show several small upward excursions with increasing cluster size. A plot of the latent heat against the entropy change for melting reveals two groups of clusters: the latent heats and entropy changes for clusters with less than 94 atoms are distinct from those for clusters with more than 93 atoms. This observation suggests that a significant change in the nature of the bonding or the structure of the clusters occurs at 93-94 atoms. Even though the melting temperatures are close to the bulk value for the larger clusters studied here, the latent heats and entropies of melting are still far from the bulk values.

  15. Influence of repetitive pulsed laser irradiation on the surface characteristics of an aluminum alloy in the melting regime

    International Nuclear Information System (INIS)

    Choi, Sung Ho; Jhang, Kyung Young

    2015-01-01

    We have investigated the influence of repetitive near-infrared (NIR) pulsed laser shots in the melting regime on the surface characteristics of an aluminum 6061-T6 alloy. Characteristics of interest include surface morphology, surface roughness, and surface hardness in the melted zone as well as the size of the melted zone. For this study, the proper pulse energy for inducing surface melting at one shot is selected using numerical simulations that calculate the variation in temperature at the laser beam spot for various input pulse energies in order to find the proper pulse energy for raising the temperature to the melting point. In this study, 130 mJ was selected as the input energy for a Nd:YAG laser pulse with a duration of 5 ns. The size of the melted zone measured using optical microscopy (OM) increased logarithmically with an increasing shot number. The surface morphology observed by scanning electron microscopy (SEM) clearly showed a re-solidified microstructure evolution after surface melting. The surface roughness and hardness were measured by atomic force microscopy (AFM) and nano-indentation, respectively. The surface roughness showed almost no variation due to the surface texturing after laser shots over 10. The hardness inside the melted zone was lower than that outside the zone because the β'' phase was transformed to a β phase or dissolved into a matrix.

  16. Using ice melting and ice rolling technologies to remove ice from sub-transmission and transmission lines at Manitoba Hydro

    International Nuclear Information System (INIS)

    Farias, A. R.

    1999-01-01

    Development of an of an Ice Storm Management program by Manitoba Hydro to reduce ice storm damage to its 8 kV feeders to 115 kV transmission lines, is discussed. The program consists of the de-icing of overhead lines, either by ice melting, or ice rolling. Ice melting involves the placement of a three-phase short at a calculated point. The term ice rolling denotes a process of mechanically stripping the ice from conductors. The most recent major ice storm experienced by Manitoba Hydro was in the winter of 1997/1998. During the period from February 6 to February 17, 1998, a total of 83 'ice melt' procedures were performed to melt the ice from 2,628 km of overhead line (7,883 km of conductor), in addition to 'ice rolling'. This paper describes Manitoba Hydro's 25-years' experience with ice melting and it also describes the advantages and disadvantages of both ice melting and ice rolling. Although not a panacea to combat the effects of ice storms, ice melting was found to be the most effective way of removing ice from overhead transmission and sub-transmission lines. Ice rolling was also found to be effective. Other tools that have been found to be useful by various utilities in combating ice storm damage include improved structure and line design, system design that provide more redundancies and emergency sources, and standby generators at critical load points

  17. Comparison between RVG UI sensor and Kodak InSight film for detection of incipient proximal caries

    International Nuclear Information System (INIS)

    Matsuda, Yukiko; Hanazawa, Tomomi; Seki, Kenji; Araki, Kazuyuki; Okano, Tomohiro

    2002-01-01

    The purpose of this study was to compare the efficacy of the four combination modes of Trophy Radio Visio Graphy (RVG) UI sensor (Trex-Trophy Radiology Inc., Marne-la-Valee, France) and Kodak InSight film (Eastman Kodak Co., Rochester, NY) for detecting proximal dental caries. Thirty extracted human upper premolars were selected. Of 60 surfaces, 25 had carious lesions in the form of small cavities, and the rest showed no evidence of caries as verified by a micro computed tomogram (micro CT; XCT Research SA+, Stratec Medizintechnik GmbH, Pforzheim, Germany). All teeth were radiographed with the paralleling technique (60 kV, 40 cm focus-to-sensor distance). Four combination modes (high-resolution caries mode-HRC; high-sensitivity caries mode-HSC; high-resolution periodontal mode-HRP; and high-resolution endo mode-HRE) were used. Exposure was set at 0.12 sec for HRC, 0.08 sec for HSC, 0.16 sec for HRP, 0.12 sec for HRE, and 0.16 sec for the Kodak InSight film. The resulting images were evaluated by three oral radiologists. The same three observers evaluated the digital images, and were allowed to use the contrast and brightness controls in doing so. Possible differences in receiver operating characteristic (ROC) curve areas among image modalities were assessed by the Friedman test. The mean ROC curve areas were 0.66±0.11 for HRC, 0.78±0.02 for HSC, 0.76±0.04 for HRE, 0.77±0.04 for HRP, and 0.71±0.09 for the Kodak InSight film. There were no statistically significant differences between HRC, HSC, HRE, HRP and the Kodak InSight film in terms of proximal caries detection. The four modes of RVG UI system are each a viable alternative to intraoral film for the detection of incipient dental caries. (author)

  18. Carbon-dioxide-rich silicate melt in the Earth's upper mantle.

    Science.gov (United States)

    Dasgupta, Rajdeep; Mallik, Ananya; Tsuno, Kyusei; Withers, Anthony C; Hirth, Greg; Hirschmann, Marc M

    2013-01-10

    The onset of melting in the Earth's upper mantle influences the thermal evolution of the planet, fluxes of key volatiles to the exosphere, and geochemical and geophysical properties of the mantle. Although carbonatitic melt could be stable 250 km or less beneath mid-oceanic ridges, owing to the small fraction (∼0.03 wt%) its effects on the mantle properties are unclear. Geophysical measurements, however, suggest that melts of greater volume may be present at ∼200 km (refs 3-5) but large melt fractions are thought to be restricted to shallower depths. Here we present experiments on carbonated peridotites over 2-5 GPa that constrain the location and the slope of the onset of silicate melting in the mantle. We find that the pressure-temperature slope of carbonated silicate melting is steeper than the solidus of volatile-free peridotite and that silicate melting of dry peridotite + CO(2) beneath ridges commences at ∼180 km. Accounting for the effect of 50-200 p.p.m. H(2)O on freezing point depression, the onset of silicate melting for a sub-ridge mantle with ∼100 p.p.m. CO(2) becomes as deep as ∼220-300 km. We suggest that, on a global scale, carbonated silicate melt generation at a redox front ∼250-200 km deep, with destabilization of metal and majorite in the upwelling mantle, explains the oceanic low-velocity zone and the electrical conductivity structure of the mantle. In locally oxidized domains, deeper carbonated silicate melt may contribute to the seismic X-discontinuity. Furthermore, our results, along with the electrical conductivity of molten carbonated peridotite and that of the oceanic upper mantle, suggest that mantle at depth is CO(2)-rich but H(2)O-poor. Finally, carbonated silicate melts restrict the stability of carbonatite in the Earth's deep upper mantle, and the inventory of carbon, H(2)O and other highly incompatible elements at ridges becomes controlled by the flux of the former.

  19. Internal stress-induced melting below melting temperature at high-rate laser heating

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Yong Seok, E-mail: yshwang@iastate.edu [Department of Aerospace Engineering, Iowa State University, Ames, Iowa 50011 (United States); Levitas, Valery I., E-mail: vlevitas@iastate.edu [Departments of Aerospace Engineering, Mechanical Engineering, and Material Science and Engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2014-06-30

    In this Letter, continuum thermodynamic and phase field approaches (PFAs) predicted internal stress-induced reduction in melting temperature for laser-irradiated heating of a nanolayer. Internal stresses appear due to thermal strain under constrained conditions and completely relax during melting, producing an additional thermodynamic driving force for melting. Thermodynamic melting temperature for Al reduces from 933.67 K for a stress-free condition down to 898.1 K for uniaxial strain and to 920.8 K for plane strain. Our PFA simulations demonstrated barrierless surface-induced melt nucleation below these temperatures and propagation of two solid-melt interfaces toward each other at the temperatures very close to the corresponding predicted thermodynamic equilibrium temperatures for the heating rate Q≤1.51×10{sup 10}K/s. At higher heating rates, kinetic superheating competes with a reduction in melting temperature and melting under uniaxial strain occurs at 902.1 K for Q = 1.51 × 10{sup 11 }K/s and 936.9 K for Q = 1.46 × 10{sup 12 }K/s.

  20. Energy Saving Melting and Revert Reduction Technology: Melting Efficiency in Die Casting Operations

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam

    2012-12-15

    This project addressed multiple aspects of the aluminum melting and handling in die casting operations, with the objective of increasing the energy efficiency while improving the quality of the molten metal. The efficiency of melting has always played an important role in the profitability of aluminum die casting operations. Consequently, die casters need to make careful choices in selecting and operating melting equipment and procedures. The capital cost of new melting equipment with higher efficiency can sometimes be recovered relatively fast when it replaces old melting equipment with lower efficiency. Upgrades designed to improve energy efficiency of existing equipment may be well justified. Energy efficiency is however not the only factor in optimizing melting operations. Melt losses and metal quality are also very important. Selection of melting equipment has to take into consideration the specific conditions at the die casting shop such as availability of floor space, average quantity of metal used as well as the ability to supply more metal during peaks in demand. In all these cases, it is essential to make informed decisions based on the best available data.

  1. Effect of melting conditions on striae in iron-bearing silicate melts

    DEFF Research Database (Denmark)

    Jensen, Martin; Yue, Yuanzheng

    2012-01-01

    of melt temperature and/or a decrease of viscosity play a more important role in decreasing the stria content. We also demonstrate that the extent of striation is influenced by the crucible materials that causes a change of redox state of the melt, and hence its viscosity. We discuss the effect of other...

  2. Olivine/melt transition metal partitioning, melt composition, and melt structure—Melt polymerization and Qn-speciation in alkaline earth silicate systems

    Science.gov (United States)

    Mysen, Bjorn O.

    2008-10-01

    The two most abundant network-modifying cations in magmatic liquids are Ca 2+ and Mg 2+. To evaluate the influence of melt structure on exchange of Ca 2+ and Mg 2+ with other geochemically important divalent cations ( m-cations) between coexisting minerals and melts, high-temperature (1470-1650 °C), ambient-pressure (0.1 MPa) forsterite/melt partitioning experiments were carried out in the system Mg 2SiO 4-CaMgSi 2O 6-SiO 2 with ⩽1 wt% m-cations (Mn 2+, Co 2+, and Ni 2+) substituting for Ca 2+ and Mg 2+. The bulk melt NBO/Si-range ( NBO/Si: nonbridging oxygen per silicon) of melt in equilibrium with forsterite was between 1.89 and 2.74. In this NBO/Si-range, the NBO/Si(Ca) (fraction of nonbridging oxygens, NBO, that form bonds with Ca 2+, Ca 2+- NBO) is linearly related to NBO/Si, whereas fraction of Mg 2+- NBO bonds is essentially independent of NBO/Si. For individual m-cations, rate of change of KD( m-Mg) with NBO/Si(Ca) for the exchange equilibrium, mmelt + Mg olivine ⇌ molivine + Mg melt, is linear. KD( m-Mg) decreases as an exponential function of increasing ionic potential, Z/ r2 ( Z: formal electrical charge, r: ionic radius—here calculated with oxygen in sixfold coordination around the divalent cations) of the m-cation. The enthalpy change of the exchange equilibrium, Δ H, decreases linearly with increasing Z/ r2 [Δ H = 261(9)-81(3)· Z/ r2 (Å -2)]. From existing information on (Ca,Mg)O-SiO 2 melt structure at ambient pressure, these relationships are understood by considering the exchange of divalent cations that form bonds with nonbridging oxygen in individual Qn-species in the melts. The negative ∂ KD( m-Mg) /∂( Z/ r2) and ∂(Δ H)/∂( Z/ r2) is because increasing Z/ r2 is because the cations forming bonds with nonbridging oxygen in increasingly depolymerized Qn-species where steric hindrance is decreasingly important. In other words, principles of ionic size/site mismatch commonly observed for trace and minor elements in crystals, also

  3. Bloomington (LL6) chondrite and its shock melt glasses

    International Nuclear Information System (INIS)

    Dodd, R.T.; Olsen, E.J.; Clarke, R.S. Jr.; National Museum of Natural History, Washington, DC; Field Museum of Natural History, Chicago, IL)

    1985-01-01

    The shock melt glasses of the Bloomington LL-group chondrite were examined using electron-beam microscopy and compared with data from studies of other shock melt glasses. Petrologic and mineralogic characterizations were also performed of the samples. The metal contents of the meteorite were almost wholly Ni-rich martensite. The glasses resembled shock melt glasses in L-group chondrites, and were indicative of isochemical melting during one melt phase, i.e., a very simple history. 12 references

  4. Individual-Based Modeling Approach to Assessment of the Impacts of Landscape Complexity and Climate on Dispersion, Detectability and Fate of Incipient Medfly Populations

    Directory of Open Access Journals (Sweden)

    Slawomir A. Lux

    2018-01-01

    Full Text Available The objective of the presented study was to demonstrate the potential of a bottom-up “ethological” approach and individual-based model of Markov-like stochastic processes, employed to gain insights into the factors driving behavior and fate of the invasive propagule, which determine the initial stages of pest invasion and “cryptic” existence of the localized, ultra-low density incipient pest populations. The applied model, PESTonFARM, is driven by the parameters derived directly from the behavior and biology of the target insect species, and spatiotemporal traits of the local terrain and climate. The model projections are actively generated by behavior of the primary causative actors of the invasion processes—individual “virtual” insects—members of the initial propagules or incipient populations. Algorithms of the model were adjusted to reflect behavior and ecology of the Mediterranean fruit fly, Ceratitis capitata, used as a case-example in the presented study. The model was parametrized based on compiled published experimental information about C. capitata behavior and development, and validated using published data from dispersion and trapping studies. The model reliably simulated behavior, development and dispersion of individual members of an invasive cohort, and allowed to quantify pest establishment and detection chances in landscapes of varying spatiotemporal complexity, host availability and climates. The results support the common view that, under optimal conditions (farmland with continuous fruit availability and suitable climate, even a single propagule of medium size (100 females usually results in pest establishment and detection within the first year post-invasion. The results demonstrate, however, that under specific sub-optimal conditions determined by the local climate, weather fluctuations and landscape topography (e.g., sub-urban, the incipient cryptic populations may occasionally continue for several

  5. Melting of the Earth's inner core.

    Science.gov (United States)

    Gubbins, David; Sreenivasan, Binod; Mound, Jon; Rost, Sebastian

    2011-05-19

    The Earth's magnetic field is generated by a dynamo in the liquid iron core, which convects in response to cooling of the overlying rocky mantle. The core freezes from the innermost surface outward, growing the solid inner core and releasing light elements that drive compositional convection. Mantle convection extracts heat from the core at a rate that has enormous lateral variations. Here we use geodynamo simulations to show that these variations are transferred to the inner-core boundary and can be large enough to cause heat to flow into the inner core. If this were to occur in the Earth, it would cause localized melting. Melting releases heavy liquid that could form the variable-composition layer suggested by an anomaly in seismic velocity in the 150 kilometres immediately above the inner-core boundary. This provides a very simple explanation of the existence of this layer, which otherwise requires additional assumptions such as locking of the inner core to the mantle, translation from its geopotential centre or convection with temperature equal to the solidus but with composition varying from the outer to the inner core. The predominantly narrow downwellings associated with freezing and broad upwellings associated with melting mean that the area of melting could be quite large despite the average dominance of freezing necessary to keep the dynamo going. Localized melting and freezing also provides a strong mechanism for creating seismic anomalies in the inner core itself, much stronger than the effects of variations in heat flow so far considered.

  6. Melting behavior of Earth's lower mantle minerals at high pressures

    Science.gov (United States)

    Fu, S.; Yang, J.; Prakapenka, V. B.; Zhang, Y.; Greenberg, E.; Lin, J. F.

    2017-12-01

    Melting behavior of the most abundant lower mantle minerals, bridgmanite and ferropericlase, at high pressure-temperature (P-T) conditions is of critical importance to understand the dynamic evolution of the early Earth and to explain the seismological and geochemical signatures in the present lowermost mantle. Theoretical calculations [1] and geodynamical models [2] suggested that partial melting of early Earth among MgO-FeO-SiO2 ternary could be located at the eutectic point where a pyrolitic composition formed for the Earth's lower mantle and the eutectic crystallization process could provide a plausible mechanism to the origin of the ultra-low velocity zones (ULVZs) near the core-mantle boundary. Here we have investigated the melting behavior of ferropericlase and Al,Fe-bearing bridgmanite in laser-heated diamond anvil cells coupled with in situ X-ray diffraction up to 120 GPa. Together with chemical and texture characterizations of the quenched samples, these results are analyzed using thermodynamic models to address the effects of iron on the liquidus and solidus temperatures as well as solid-liquid iron partitioning and the eutectic point in ferropericlase-bridgmanite existing system at lower-mantle pressure. In this presentation, we discuss the application of these results to better constrain the seismic observations of the deep lowermost mantle such as large low shear wave velocity provinces (LLSVPs) and ULVZs. We will also discuss the geochemical consequences of the ferropericlase-bridgmanite melting due to the changes in the electronic spin and valence states of iron in the system. ADDIN EN.REFLIST 1. Boukaré, C.E., Y. Ricard, and G. Fiquet, Thermodynamics of the MgO-FeO-SiO2 system up to 140 GPa: Application to the crystallization of Earth's magma ocean. Journal of Geophysical Research: Solid Earth, 2015. 120(9): p. 6085-6101. 2. Labrosse, S., J. Hernlund, and N. Coltice, A crystallizing dense magma ocean at the base of the Earth's mantle. Nature, 2007

  7. Prevalencia de lesiones incipientes de caries dental en niños escolares Prevalence of incipient lesions of dental caries in school children

    Directory of Open Access Journals (Sweden)

    Nayda Nasco Hidalgo

    2008-06-01

    Full Text Available OBJETIVOS: determinar la prevalencia de lesiones incipientes de caries dental en los niños de 6-11 años de la escuela primaria "José A Echeverría," municipio Plaza de la Revolución en el período de enero a diciembre del 2006, identificar en el grupo estudiado, la frecuencia de niños según número de lesiones incipientes y la frecuencia de lesiones incipientes por ubicación del diente en la arcada y por superficie dentaria. MÉTODOS: se realizó un estudio observacional descriptivo de corte transversal, el universo estuvo integrado por todos los niños que estuvieran en esas edades y que cumplieran con los criterios de inclusión, para un total de 236, los cuales fueron examinados al aire libre y con luz natural, utilizando el método visual- táctil suave. Los dientes se limpiaron con algodón y se secaron con peras de aire para detectar la presencia de lesiones incipientes de caries, las cuales fueron señalizadas en un modelo de dentigrama, en el lugar correspondiente a la superficie afectada. RESULTADOS: se halló que el 22,5 % de los escolares examinados presentaba estas lesiones, de ellos el 60,1 % correspondió al sexo femenino; el 19,5 % del total de niños presentó una lesión y sólo el 3% tenia dos lesiones incipientes de caries dental; el 79,2 % de las mismas se encontraron en los dientes posteriores, fueron las superficies lisas las más afectadas con un 45,3 %. CONCLUSIONES: Alrededor de la cuarta parte de los niños estudiados presentaron lesiones incipientes de caries, siendo el sexo femenino el más afectado. Del total de niños que poseían lesiones incipientes, la mayor cifra correspondió a los que presentaban una lesión. Los dientes posteriores fueron los más afectados por lesiones incipientes. Las superficies lisas mostraron más lesiones incipientes que las oclusales y proximalesOBJECTIVES: to determine the prevalence of incipient lesions of dental caries in children aged 6-11 of "José A Echeverría" Primary

  8. A high sensibility technique to detect the incipient defects in high tension bushings; Una tecnica de alta sensibilidad para detectar defectos incipientes en boquillas de alta tension

    Energy Technology Data Exchange (ETDEWEB)

    Robles Pimentel, Edgar; Mestizo Rivera, Antolin; Romero Camberos, Ramon [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1995-12-31

    In this article a testing technique to locate incipient faults in transformer bushings is reported, specifically the one related to the internal disconnection of the capacitive tap, which is exemplified with a device having a problem of this kind. [Espanol] En el presente articulo se reporta una tecnica de prueba para localizar fallas incipientes en las boquillas de los transformadores, especificamente la relacionada con la desconexion interna del tap capacitivo, lo cual se ejemplifica con un dispositivo que padece un problema de ese tipo.

  9. SLUDGE MASS REDUCTION: PRIMARY COMPOSITIONAL FACTORS THAT INFLUENCE MELT RATE FOR FUTURE SLUDGE BATCH PROJECTIONS

    International Nuclear Information System (INIS)

    Newell, J; Miller, D; Stone, M; Pickenheim, B

    2008-01-01

    510 based system without Al-dissolution relative to the Frit 418 based system with Al-dissolution. Though the without aluminum dissolution scenario suggests a slightly higher melt rate with frit 510, several points must be taken into consideration: (1) The MRF does not have the ability to assess liquid feeds and, thus, rheology impacts. Instead, the MRF is a 'static' test bed in which a mass of dried melter feed (SRAT product plus frit) is placed in an 'isothermal' furnace for a period of time to assess melt rate. These conditions, although historically effective in terms of identifying candidate frits for specific sludge batches and mapping out melt rate versus waste loading trends, do not allow for assessments of the potential impact of feed rheology on melt rate. That is, if the rheological properties of the slurried melter feed resulted in the mounding of the feed in the melter (i.e., the melter feed was thick and did not flow across the cold cap), melt rate and/or melter operations (i.e., surges) could be negatively impacted. This could affect one or both flowsheets. (2) Waste throughput factors were not determined for Frit 510 and Frit 418 over multiple waste loadings. In order to provide insight into the mission life versus canister count question, one needs to define the maximum waste throughput for both flowsheets. Due to funding limitations, the melt rate testing only evaluated melt rate at a fixed waste loading. (3) DWPF will be processing SB5 through their facility in mid-November 2008. Insight into the over arching questions of melt rate, waste throughput, and mission life can be obtained directly from the facility. It is recommended that processing of SB5 through the facility be monitored closely and that data be used as input into the decision making process on whether to implement Al-dissolution for future sludge batches

  10. Activities in Cu2S-FeS-SnS melts at 1200 °C

    Science.gov (United States)

    Eric, R. Hurman

    1993-04-01

    The dew-point technique was used to measure the vapor pressures of SnS over liquid sulfides of the system Cu2S-FeS-SnS at 1200 °C. Activities of SnS were generated from the measured vapor pressures of SnS. Activities of Cu2S and FeS were evaluated both in binary and ternary melts by Gibbs-Duhem calculations from the known SnS activity data. The systems Cu2S-SnS and Cu2S-FeS exhibit negative departures from ideal behavior, while FeS-SnS melts exhibit positive deviations.

  11. Viscosity of Hg(0.84)Zn(0.16)Te Pseudobinary Melt

    Science.gov (United States)

    Mazuruk, K.; Su, Ching-Hua; Sha, Yi-Gao; Lehoczky, S. L.

    1996-01-01

    An oscillating-cup viscometer was developed to measure viscosity of molten HgZnTe ternary semiconductor alloys. Data were collected for the pseudobinary Hg(0.84)Zn(0.16)Te melt between 770 and 850 C. The kinematic viscosity was found to vary from approximately 1.1 to 1.4 x 10(sup -3)sq cm/s. A slow relaxation phenomena was also observed for temperatures from the melting point of 770 to approx. 800 C. Possible mechanisms for this effect are discussed.

  12. Method for preparation of melts of alkali metal chlorides with highly volatile polyvalent metal chlorides

    International Nuclear Information System (INIS)

    Salyulev, A.B.; Kudyakov, V.Ya.

    1990-01-01

    A method for production of alkali metal (Cs, Rb, K) chloride melts with highly volatile polyvalent metal chlorides is suggested. The method consists, in saturation of alkali metal chlorides, preheated to the melting point, by volatile component vapours (titanium tetrachloride, molybdenum or tantalum pentachloride) in proportion, corresponding to the composition reguired. The saturation is realized in an evacuated vessel with two heating areas for 1-1.5 h. After gradual levelling of temperature in both areas the product is rapidly cooled. 1 fig.; 1 tab

  13. Entangled Polymer Melts in Extensional Flow

    DEFF Research Database (Denmark)

    Hengeller, Ludovica

    . On the other hand, addition of low-volatility solvents to polymers is also a common industrial practice that others a means for lowering the Tg of the polymers. Moreover industrial polymers present a wide distribution of chain lengths and/or branched architectures that strongly influence their response....... Understanding the behaviour of polymer melts and solutions in complex non-linearflows is crucial for the design of polymeric materials and polymer processes. Through rheological characterization, in shear and extensional flow, of model polymer systems,i.e. narrow molar mass distribution polymer melts......Many commercial materials derived from synthetic polymers exhibit a complex response under different processing operations such as fiber formation, injection moulding,film blowing, film casting or coatings. They can be processed both in the solid or in the melted state. Often they may contain two...

  14. Melting of peridotite to 140 gigapascals.

    Science.gov (United States)

    Fiquet, G; Auzende, A L; Siebert, J; Corgne, A; Bureau, H; Ozawa, H; Garbarino, G

    2010-09-17

    Interrogating physical processes that occur within the lowermost mantle is a key to understanding Earth's evolution and present-day inner composition. Among such processes, partial melting has been proposed to explain mantle regions with ultralow seismic velocities near the core-mantle boundary, but experimental validation at the appropriate temperature and pressure regimes remains challenging. Using laser-heated diamond anvil cells, we constructed the solidus curve of a natural fertile peridotite between 36 and 140 gigapascals. Melting at core-mantle boundary pressures occurs at 4180 ± 150 kelvin, which is a value that matches estimated mantle geotherms. Molten regions may therefore exist at the base of the present-day mantle. Melting phase relations and element partitioning data also show that these liquids could host many incompatible elements at the base of the mantle.

  15. Analysis of Picosecond Pulsed Laser Melted Graphite

    Science.gov (United States)

    Steinbeck, J.; Braunstein, G.; Speck, J.; Dresselhaus, M. S.; Huang, C. Y.; Malvezzi, A. M.; Bloembergen, N.

    1986-12-01

    A Raman microprobe and high resolution TEM have been used to analyze the resolidified region of liquid carbon generated by picosecond pulse laser radiation. From the relative intensities of the zone center Raman-allowed mode for graphite at 1582 cm{sup -1} and the disorder-induced mode at 1360 cm{sup -1}, the average graphite crystallite size in the resolidified region is determined as a function of position. By comparison with Rutherford backscattering spectra and Raman spectra from nanosecond pulsed laser melting experiments, the disorder depth for picosecond pulsed laser melted graphite is determined as a function of irradiating energy density. Comparisons of TEM micrographs for nanosecond and picosecond pulsed laser melting experiments show that the structure of the laser disordered regions in graphite are similar and exhibit similar behavior with increasing laser pulse fluence.

  16. Analysis of picosecond pulsed laser melted graphite

    Energy Technology Data Exchange (ETDEWEB)

    Steinbeck, J.; Braunstein, G.; Speck, J.; Dresselhaus, M.S.; Huang, C.Y.; Malvezzi, A.M.; Bloembergen, N.

    1986-01-01

    A Raman microprobe and high resolution TEM have been used to analyze the resolidified region of liquid carbon generated by picosecond pulse laser radiation. From the relative intensities of the zone center Raman-allowed mode for graphite at 1582 cm/sup -1/ and the disorder-induced mode at 1360 cm/sup -1/, the average graphite crystallite size in the resolidified region is determined as a function of position. By comparison with Rutherford backscattering spectra and Raman spectra from nonosecond pulsed laser melting experiments, the disorder depth for picosecond pulsed laser melted graphite is determined as a function of irradiating energy density. Comparisons of TEM micrographs for nanosecond and picosecond pulsed laser melting experiments show that the structure of the laser disordered regions in graphite are similar and exhibit similar behavior with increasing laser pulse fluence.

  17. Scrap uranium recycling via electron beam melting

    International Nuclear Information System (INIS)

    McKoon, R.

    1993-11-01

    A program is underway at the Lawrence Livermore National Laboratory (LLNL) to recycle scrap uranium metal. Currently, much of the material from forging and machining processes is considered radioactive waste and is disposed of by oxidation and encapsulation at significant cost. In the recycling process, uranium and uranium alloys in various forms will be processed by electron beam melting and continuously cast into ingots meeting applicable specifications for virgin material. Existing vacuum processing facilities at LLNL are in compliance with all current federal and state environmental, safety and health regulations for the electron beam melting and vaporization of uranium metal. One of these facilities has been retrofitted with an auxiliary electron beam gun system, water-cooled hearth, crucible and ingot puller to create an electron beam melt furnace. In this furnace, basic process R ampersand D on uranium recycling will be performed with the goal of eventual transfer of this technology to a production facility

  18. Scleral melt following Retisert intravitreal fluocinolone implant

    Directory of Open Access Journals (Sweden)

    Georgalas I

    2014-11-01

    Full Text Available Ilias Georgalas,1 Chrysanthi Koutsandrea,1 Dimitrios Papaconstantinou,1 Dimitrios Mpouritis,1 Petros Petrou1,2 1Ophthalmology Department, University of Athens, Athens, Greece; 2Moorfields Eye Hospital, London, UKAbstract: Intravitreal fluocinolone acetonide implant (Retisert has a high potency, a low solubility, and a very short duration of action in the systemic circulation, enabling the steroid pellet to be small and reducing the risk of systemic side effects. Scleral melt has not been reported as a possible complication of Retisert implant. The authors describe the occurrence of scleral melt 18 months after the implantation of fluocinolone acetonide implant in a 42-year-old Caucasian woman. To the authors’ knowledge, this is the first report of this possible complication.Keywords: Retisert, scleral melt, complication, surgical management

  19. Analysis of picosecond pulsed laser melted graphite

    International Nuclear Information System (INIS)

    Steinbeck, J.; Braunstein, G.; Speck, J.; Dresselhaus, M.S.; Huang, C.Y.; Malvezzi, A.M.; Bloembergen, N.

    1986-01-01

    A Raman microprobe and high resolution TEM have been used to analyze the resolidified region of liquid carbon generated by picosecond pulse laser radiation. From the relative intensities of the zone center Raman-allowed mode for graphite at 1582 cm -1 and the disorder-induced mode at 1360 cm -1 , the average graphite crystallite size in the resolidified region is determined as a function of position. By comparison with Rutherford backscattering spectra and Raman spectra from nonosecond pulsed laser melting experiments, the disorder depth for picosecond pulsed laser melted graphite is determined as a function of irradiating energy density. Comparisons of TEM micrographs for nanosecond and picosecond pulsed laser melting experiments show that the structure of the laser disordered regions in graphite are similar and exhibit similar behavior with increasing laser pulse fluence

  20. Selective Laser Melting of Pure Copper

    Science.gov (United States)

    Ikeshoji, Toshi-Taka; Nakamura, Kazuya; Yonehara, Makiko; Imai, Ken; Kyogoku, Hideki

    2018-03-01

    Appropriate building parameters for selective laser melting of 99.9% pure copper powder were investigated at relatively high laser power of 800 W for hatch pitch in the range from 0.025 mm to 0.12 mm. The highest relative density of the built material was 99.6%, obtained at hatch pitch of 0.10 mm. Building conditions were also studied using transient heat analysis in finite element modeling of the liquidation and solidification of the powder layer. The estimated melt pool length and width were comparable to values obtained by observations using a thermoviewer. The trend for the melt pool width versus the hatch pitch agreed with experimental values.

  1. Melt spun aluminium alloys for moulding optics

    Science.gov (United States)

    Gubbels, G.; Tegelaers, L.; Senden, R.

    2013-09-01

    Melt spinning is a rapid quenching process that makes it possible to create materials with a very fine microstructure. Due to this very fine microstructure the melt spinning process is an enabler for diamond turning optics and moulds without the need of post-polishing. Using diamond turning of melt spun aluminium one can achieve coating concept RSA-905 can be upgraded to a competitive alternative to steel in terms of price, performance and logistics. This paper presents some recent developments for improved mould performance of such concept. Hardness, wear resistance and adhesion are topics of interest and they can be applied by special coatings such as diamond-like carbon (DLC) and chromium nitride (CrN). These coatings make the aluminium alloy suitable for moulding mass production of small as well as larger optics, such as spectacle lenses.

  2. The rock melting approach to drilling

    Energy Technology Data Exchange (ETDEWEB)

    Cort, G.E.; Goff, S.J.; Rowley, J.C.; Neudecker, J.W. Jr.; Dreesen, D.S.; Winchester, W.

    1993-09-01

    During the early and mid-1970`s the Los Alamos National Laboratory demonstrated practical applications of drilling and coring using an electrically-heated graphite, tungsten, or molybdenum penetrator that melts a hole as it is slowly pushed through the rock or soil. The molten material consolidates into a rugged glass lining that prevents hole collapse; minimizes the potential for cross-flow, lost circulation, or the release of hazardous materials without casing operations; and produces no cuttings in porous or low density (<1.7 g/cc) formations. Because there are no drilling fluids required, the rock melting approach reduces waste handling, treatment and disposal. Drilling by rock melting has been demonstrated to depths up to 30 m in caliche, clay, alluvium, cobbles, sand, basalt, granite, and other materials. Penetrating large cobbles without debris removal was achieved by thermal stress fracturing and lateral extrusion of portions of the rock melt into the resulting cracks. Both horizontal and vertical holes in a variety of diameters were drilled in these materials using modular, self-contained field units that operate in remote areas. Because the penetrator does not need to rotate, steering by several simple approaches is considered quite feasible. Melting is ideal for obtaining core samples in alluvium and other poorly consolidated soils since the formed-in-place glass liner stabilizes the hole, encapsulates volatile or hazardous material, and recovers an undisturbed core. Because of the relatively low thermal conductivity of rock and soil materials, the heat-affected zone beyond the melt layer is very small, <1 inch thick. Los Alamos has begun to update the technology and this paper will report on the current status of applications and designs for improved drills.

  3. Structure of polyvalent metal halide melts

    International Nuclear Information System (INIS)

    Tosi, M.P.

    1990-12-01

    A short review is given of recent progress in determining and understanding the structure of molten halide salts involving polyvalent metal ions. It covers the following three main topics: (i) melting mechanisms and types of liquid structure for pure polyvalent-metal chlorides; (ii) geometry and stability of local coordination for polyvalent metal ions in molten mixtures of their halides with alkali halides; and (iii) structure breaking and electron localization on addition of metal to the melt. (author). 28 refs, 3 figs, 1 tab

  4. Chemical reactions in solvents and melts

    CERN Document Server

    Charlot, G

    1969-01-01

    Chemical Reactions in Solvents and Melts discusses the use of organic and inorganic compounds as well as of melts as solvents. This book examines the applications in organic and inorganic chemistry as well as in electrochemistry. Organized into two parts encompassing 15 chapters, this book begins with an overview of the general properties and the different types of reactions, including acid-base reactions, complex formation reactions, and oxidation-reduction reactions. This text then describes the properties of inert and active solvents. Other chapters consider the proton transfer reactions in

  5. A characterization of Greenland Ice Sheet surface melt and runoff in contemporary reanalyses and a regional climate model

    Science.gov (United States)

    Cullather, Richard; Nowicki, Sophie; Zhao, Bin; Koenig, Lora

    2016-02-01

    For the Greenland Ice Sheet (GrIS), large-scale melt area has increased in recent years and is detectable via remote sensing, but its relation to runoff is not known. Historical, modeled melt area and runoff from Modern-Era Retrospective Analysis for Research and Applications (MERRA-Replay), the Interim Re-Analysis of the European Centre for Medium Range Weather Forecasts (ERA-I), the Climate Forecast System Reanalysis (CFSR), the Modèle Atmosphérique Régional (MAR), and the Arctic System Reanalysis (ASR) are examined. These sources compare favorably with satellite-derived estimates of surface melt area for the period 2000-2012. Spatially, the models markedly disagree on the number of melt days in the interior of the southern part of the ice sheet, and on the extent of persistent melt areas in the northeastern GrIS. Temporally, the models agree on the mean seasonality of daily surface melt and on the timing of large-scale melt events in 2012. In contrast, the models disagree on the amount, seasonality, spatial distribution, and temporal variability of runoff. As compared to global reanalyses, time series from MAR indicate a lower correlation between runoff and melt area (r2 = 0.805). Runoff in MAR is much larger in the second half of the melt season for all drainage basins, while the ASR indicates larger runoff in the first half of the year. This difference in seasonality for the MAR and to an extent for the ASR provide a hysteresis in the relation between runoff and melt area, which is not found in the other models. The comparison points to a need for reliable observations of surface runoff.

  6. The Microwave Properties of Simulated Melting Precipitation Particles: Sensitivity to Initial Melting

    Science.gov (United States)

    Johnson, B. T.; Olson, W. S.; Skofronick-Jackson, G.

    2016-01-01

    A simplified approach is presented for assessing the microwave response to the initial melting of realistically shaped ice particles. This paper is divided into two parts: (1) a description of the Single Particle Melting Model (SPMM), a heuristic melting simulation for ice-phase precipitation particles of any shape or size (SPMM is applied to two simulated aggregate snow particles, simulating melting up to 0.15 melt fraction by mass), and (2) the computation of the single-particle microwave scattering and extinction properties of these hydrometeors, using the discrete dipole approximation (via DDSCAT), at the following selected frequencies: 13.4, 35.6, and 94.0GHz for radar applications and 89, 165.0, and 183.31GHz for radiometer applications. These selected frequencies are consistent with current microwave remote-sensing platforms, such as CloudSat and the Global Precipitation Measurement (GPM) mission. Comparisons with calculations using variable-density spheres indicate significant deviations in scattering and extinction properties throughout the initial range of melting (liquid volume fractions less than 0.15). Integration of the single-particle properties over an exponential particle size distribution provides additional insight into idealized radar reflectivity and passive microwave brightness temperature sensitivity to variations in size/mass, shape, melt fraction, and particle orientation.

  7. Effect of water on mantle melting and magma differentiation, as modeled using Adiabat_1ph 3.0

    Science.gov (United States)

    Antoshechkina, P. M.; Asimow, P. D.; Hauri, E. H.; Luffi, P. I.

    2010-12-01

    MELTS [1] and pMELTS [2] are widely used for modeling hydrous magma differentiation and water-saturated mantle melting, respectively. In pHMELTS [3] the water species can partition into melt, pure vapor, and hydrous or nominally anhydrous minerals so that phase relations for water-undersaturated systems may also be constructed. Adiabat_1ph is a text-based front end to the (pH)MELTS algorithms; in version 3.0 (Antoshechkina and Asimow, this meeting) we have added tools to further explore the effect of water on melting and fractional crystallization. Asimow and coworkers developed two schemes for fractionation-correction of major and trace elements: a forward model that considers the effects of water, pressure, and fO2 on the liquid line of descent (LLD) [3] and a hybrid back- and forward-fractionation model that may be used for individual samples when trends are poorly defined [4]. An extensive melt inclusion dataset for the Mariana Trough [5] shows evidence for simultaneous fractionation and degassing, so we have adapted routines from [4] to cope with hydrous conditions. For H2O approached as incremental feed of the same agent into a solid whose composition progressively modifies as it reacts with melt. The observation that incremental flux melting of peridotites leads to a broader diversity and steeper gradients in residue compositions than batch fluxing [6] also holds for water-fluxed melting of peridotites. Liquids resulting from the two mechanisms differ most at the point of highest melt/rock ratio. Melts generated by incremental fluxing are poorer in Si and richer in Al and Fe than those resulting from batch water addition, implying that hydrous melts traversing the lithosphere via porous flow tend to appear deeper and hotter than do melts traveling in conduits. [1] Ghiorso & Sack 1995 CMP [2] Ghiorso et al. 2002 [3] Asimow et al. 2004 [4] Cooper et al 2004 EPSL [5] Shaw, Hauri et al., in prep [6] Luffi et al. 2009 EOS

  8. Melting of KCl and pressure calibration from in situ ionic conductivity measurements in a multi-anvil apparatus

    Science.gov (United States)

    Li, J.; Dong, J.; Zhu, F.

    2017-12-01

    Melting plays an unparalleled role in planetary differentiation processes including the formation of metallic cores, basaltic crusts, and atmospheres. Knowledge of the melting behavior of Earth materials provides critical constraints for establishing the Earth's thermal structure, interpreting regional seismic anomalies, and understanding the nature of chemical heterogeneity. Measuring the melting points of compressed materials, however, have remained challenging mainly because melts are often mobile and reactive, and temperature and pressure gradients across millimeter or micron-sized samples introduce large uncertainties in melting detection. Here the melting curve of KCl was determined through in situ ionic conductivity measurements, using the multi-anvil apparatus at the University of Michigan. The method improves upon the symmetric configuration that was used recently for studying the melting behaviors of NaCl, Na2CO3, and CaCO3 (Li and Li 2015 American Mineralogist, Li et al. 2017 Earth and Planetary Science Letters). In the new configuration, the thermocouple and electrodes are placed together with the sample at the center of a cylindrical heater where the temperature is the highest along the axis, in order to minimize uncertainties in temperature measurements and increase the stability of the sample and electrodes. With 1% reproducibility in melting point determination at pressures up to 20 GPa, this method allows us to determine the sample pressure to oil load relationship at high temperatures during multiple heating and cooling cycles, on the basis of the well-known melting curves of ionic compounds. This approach enables more reliable pressure measurements than relying on a small number of fixed-point phase transitions. The new data on KCl bridge the gap between the piston-cylinder results up to 4 GPa (Pistorius 1965 J. of Physics and Chemistry of Solids) and several diamond-anvil cell data points above 20 GPa (Boehler et al. 1996 Physical Review). We

  9. A quasimechanism of melt acceleration in the thermal decomposition of crystalline organic solids

    Energy Technology Data Exchange (ETDEWEB)

    Henson, Bryan F [Los Alamos National Laboratory

    2009-01-01

    It has been know for half a century that many crystalline organic solids undergo an acceleration in the rate of thermal decomposition as the melting temperature is approached. This acceleration terminates at the melting point, exhibiting an Arrhenius-like temperature dependence in the faster decomposition rate from the liquid phase. This observation has been modeled previously using various premelting behaviors based on e.g. freezing point depression induced by decomposition products or solvent impurities. These models do not, however, indicate a mechanism for liquid formation and acceleration which is an inherent function of the bulk thermodynamics of the molecule. Here we show that such an inherent thermodynamic mechanism for liquid formation exists in the form of the so-called quasi-liquid layer at the solid surface. We explore a kinetic mechanism which describes the acceleration of rate and is a function of the free energies of sublimation and vaporization. We construct a differential rate law from these thermodynamic free energies and a normalized progress variable. We further construct a reduced variable formulation of the model which is a simple function of the metastable liquid activity below the melting point, and show that it is applicable to the observed melt acceleration in several common organic crystalline solids. A component of the differential rate law, zero order in the progress variable, is shown to be proportional to the thickness of the quasiliquid layer predicted by a recent thermodynamic theory for this phenomenon. This work therefore serves not only to provide new insight into thermal decomposition in a broad class or organic crystalline solids, but also further validates the underlying thermodynamic nature of the phenomenon of liquid formation on the molecular surface at temperatures below the melting point.

  10. Recent Changes in Arctic Sea Ice Melt Onset, Freeze-Up, and Melt Season Length

    Science.gov (United States)

    Markus, Thorsten; Stroeve, Julienne C.; Miller, Jeffrey

    2010-01-01

    In order to explore changes and trends in the timing of Arctic sea ice melt onset and freeze-up and therefore melt season length, we developed a method that obtains this information directly from satellite passive microwave data, creating a consistent data set from 1979 through present. We furthermore distinguish between early melt (the first day of the year when melt is detected) and the first day of continuous melt. A similar distinction is made for the freeze-up. Using this method we analyze trends in melt onset and freeze-up for 10 different Arctic regions. In all regions except for the Sea of Okhotsk, which shows a very slight and statistically insignificant positive trend (O.4 days/decade), trends in melt onset are negative, i.e. towards earlier melt. The trends range from -1.0day/decade for the Bering Sea to -7.3 days/decade for the East Greenland Sea. Except for the Sea of Okhotsk all areas also show a trend towards later autumn freeze onset. The Chukchi/Beaufort Seas and Laptev/East Siberian Seas observe the strongest trends with 7 days/decade. For the entire Arctic, the melt season length has increased by about 20 days over the last 30 years. Largest trends of over 1O days/decade are seen for Hudson Bay, the East Greenland Sea the Laptev/East Siberian Seas, and the Chukchi/Beaufort Seas. Those trends are statistically significant a1 the 99% level.

  11. Thermal interaction in crusted melt jets with large-scale structures

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, Ken-ichiro; Sotome, Fuminori; Ishikawa, Michio [Hokkaido Univ., Sapporo (Japan). Faculty of Engineering

    1998-01-01

    The objective of the present study is to experimentally observe thermal interaction which would be capable of triggering due to entrainment, or entrapment in crusted melt jets with `large-scale structure`. The present experiment was carried out by dropping molten zinc and molten tin of 100 grams, of which mass was sufficient to generate large-scale structures of melt jets. The experimental results show that the thermal interaction of entrapment type occurs in molten-zinc jets with rare probability, and the thermal interaction of entrainment type occurs in molten tin jets with high probability. The difference of thermal interaction between molten zinc and molten tin may attribute to differences of kinematic viscosity and melting point between them. (author)

  12. Impact of melting heat transfer and nonlinear radiative heat flux mechanisms for the generalized Burgers fluids

    Directory of Open Access Journals (Sweden)

    Waqar Azeem Khan

    Full Text Available The present paper deals with the analysis of melting heat and mass transfer characteristics in the stagnation point flow of an incompressible generalized Burgers fluid over a stretching sheet in the presence of non-linear radiative heat flux. A uniform magnetic field is applied normal to the flow direction. The governing equations in dimensional form are reduced to a system of dimensionless expressions by implementation of suitable similarity transformations. The resulting dimensionless problem governing the generalized Burgers is solved analytically by using the homotopy analysis method (HAM. The effects of different flow parameters like the ratio parameter, magnetic parameter, Prandtl number, melting parameter, radiation parameter, temperature ratio parameter and Schmidt number on the velocity, heat and mass transfer characteristics are computed and presented graphically. Moreover, useful discussions in detail are carried out with the help of plotted graphs and tables. Keywords: Generalized Burgers fluid, Non-linear radiative flow, Magnetic field, Melting heat transfer

  13. Experiments on transient melting of tungsten by ELMs in ASDEX Upgrade

    Science.gov (United States)

    Krieger, K.; Balden, M.; Coenen, J. W.; Laggner, F.; Matthews, G. F.; Nille, D.; Rohde, V.; Sieglin, B.; Giannone, L.; Göths, B.; Herrmann, A.; de Marne, P.; Pitts, R. A.; Potzel, S.; Vondracek, P.; ASDEX-Upgrade Team; EUROfusion MST1 Team

    2018-02-01

    Repetitive melting of tungsten by power transients originating from edge localized modes (ELMs) has been studied in ASDEX Upgrade. Tungsten samples were exposed to H-mode discharges at the outer divertor target plate using the divertor manipulator II (DIM-II) system (Herrmann et al 2015 Fusion Eng. Des. 98–9 1496–9). Designed as near replicas of the geometries used also in separate experiments on the JET tokamak (Coenen et al 2015 J. Nucl. Mater. 463 78–84 Coenen et al 2015 Nucl. Fusion 55 023010; Matthews et al 2016 Phys. Scr. T167 7), the samples featured a misaligned leading edge and a sloped ridge respectively. Both structures protrude above the default target plate surface thus receiving an increased fraction of the parallel power flux. Transient melting by ELMs was induced by moving the outer strike point to the sample location. The temporal evolution of the measured current flow from the samples to vessel potential confirmed transient melting. Current magnitude and dependency from surface temperature provided strong evidence for thermionic electron emission as main origin of the replacement current driving the melt motion. The different melt patterns observed after exposures at the two sample geometries support the thermionic electron emission model used in the MEMOS melt motion code, which assumes a strong decrease of the thermionic net current at shallow magnetic field to surface angles (Pitts et al 2017 Nucl. Mater. Energy 12 60–74). Post exposure ex situ analysis of the retrieved samples show recrystallization of tungsten at the exposed surface areas to a depth of up to several mm. The melt layer transport to less exposed surface areas leads to ratcheting pile up of re-solidified debris with zonal growth extending from the already enlarged grains at the surface.

  14. A melt evolution model for Kerimasi volcano, Tanzania: Evidence from carbonate melt inclusions in jacupirangite

    Science.gov (United States)

    Káldos, Réka; Guzmics, Tibor; Mitchell, Roger H.; Dawson, John Barry; Milke, Ralf; Szabó, Csaba

    2015-12-01

    This study presents compositional data for a statistically significant number (n = 180) of heated and quenched (recreated) carbonate melt inclusions trapped in magnetite and clinopyroxene in jacupirangite from Kerimasi volcano (Tanzania). On the basis of homogenization experiments for clinopyroxene-hosted melt inclusions and forsterite-monticellite-calcite phase relations, a range of 1000 to 900 °C is estimated for their crystallization temperatures. Petrographic observations and geochemical data show that during jacupirangite crystallization, a CaO-rich and alkali-"poor" carbonate melt (relative to Oldoinyo Lengai natrocarbonatite) existed and was entrapped in the precipitating magnetite, forming primary melt inclusions, and was also enclosed in previously crystallized clinopyroxene as secondary melt inclusions. The composition of the trapped carbonate melts in magnetite and clinopyroxene is very similar to the parental melt of Kerimasi calciocarbonatite; i.e., enriched in Na2O, K2O, F, Cl and S, but depleted in SiO2 and P2O5 relative to carbonate melts entrapped at an earlier stage and higher temperature (1050-1100 °C) during the formation of Kerimasi afrikandite. Significant compositional variation is shown by the major minerals of Kerimasi plutonic rocks (afrikandite, jacupirangite and calciocarbonatite). Magnetite and clinopyroxene in the jacupirangite are typically transitional in composition between those of afrikandite and calciocarbonatite. These data suggest that the jacupirangite represents an intermediate stage between the formation of afrikandite and calciocarbonatite. Jacupirangite most probably formed when immiscible silicate and carbonate melts separated from the afrikandite body, although the carbonate melt was not separated completely from the silicate melt fraction. In general, during the evolution of the carbonate melt at Kerimasi, concentrations of P2O5 and SiO2 decreased, whereas volatile content (alkalis, S, F, Cl and H2O) increased

  15. Colloidal glass transition in unentangled polymer nanocomposite melts

    International Nuclear Information System (INIS)

    Anderson, Benjamin J; Zukoski, Charles F

    2009-01-01

    The linear and non-linear rheology of a high volume fraction particle filled unentangled polymer melt is measured. The particles in the polymer melt behave like hard spheres as the particle volume fraction is raised. At high volume fractions, the suspension develops a plateau elastic modulus. Over the frequency range of the elastic modulus plateau, the viscous modulus develops a minimum and a maximum. The frequencies of the two local extrema initially have critical power law scaling, suggesting the approach of a singular glass transition. At higher volume fractions in excess of the glass transition, the viscous modulus continues to show a well defined minimum and a well defined maximum. The non-linear moduli show a single perturbative yield point beyond which the suspension softens. The yielding behavior of the nanocomposite is shown to be sensitive to the strain frequency and the proximity of the strain frequency to the maximum frequency for the linear viscous modulus from linear rheology which characterizes thermal relaxation of glassy particle clusters in the zero strain limit. The linear and non-linear measurements are compared against a recently developed mechanical theory for colloidal glasses.

  16. Safety rod/thimble melt failure characterization experiments

    International Nuclear Information System (INIS)

    Stoots, C.M.; Hawkes, G.L.

    1992-05-01

    The Department of Energy (DOE) requested that he INEL perform experiments to study the thermal failure characteristics of a simulated Savannah River Site nuclear reactor safety rod and its surrounding thimble assembly. An electrically heated stainless steel rod simulated a reactor safety rod located eccentrically or concentrically within a perforated aluminum guide tube or thimble. A total of 37 experiments were conducted for a range of power levels and safety rod/thimble relative orientations. Video tapes were made of the four failure tests that were conducted to the melting point of the thimble. Although the primary emphasis of the experiments were to characterize the melting of the thimble qualitatively, experimental transient measurements included heater voltage and current, heater surface temperatures, aluminum thimble temperatures, and ambient temperature. Numerical studies were also performed in support of the experiments and data interpretation. Two finite element models were created to model the heat conduction-radiation between the stainless steel heater and thimble. The predicted temperatures were in good agreement with the experimental results

  17. Pressure Melting and Ice Skating / Bunsen Burner

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 5. Pressure Melting and Ice Skating / Bunsen Burner - Revisited. Classroom Volume 1 Issue 5 May 1996 pp 71-78. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/001/05/0071-0078. Resonance ...

  18. Record Summer Melt in Greenland in 2010

    NARCIS (Netherlands)

    Tedesco, M.; Fettweis, X.; van den Broeke, M.R.; van de Wal, R.S.W.; Smeets, C.J.P.P.; van de Berg, W.J.; Serreze, M.C.; Box, J.E.

    2011-01-01

    As Arctic temperatures increase, there is growing concern about the melting of the Greenland ice sheet, which reached a new record during the summer of 2010. Understanding the changing surface mass balance of the Greenland ice sheet requires appreciation of the close links among changes in surface

  19. Hot-Melt Adhesive Attachment System

    Science.gov (United States)

    Fox, R. L.; Frizzell, A. W.; Little, B. D.; Progar, D. J.; Coultrip, R. H.; Couch, R. H.; Stein, B. A.; Buckley, J. D.; St. Clair, T. L.; Gleason, J. R.

    1983-01-01

    Adhesive system is as effective on Earth as in space. Fiberglass cloth mounted in head assembly. When adhesive reaches melt temperature head is attached to metals composites, ceramics, and other materials. Once attached, head cooled rapidly for quick stick. Used to tether tools or attach temporary scaffolding to walls, buildings, or beams.

  20. Stress Relaxation in Entangled Polymer Melts

    DEFF Research Database (Denmark)

    Hou, Ji-Xuan; Svaneborg, Carsten; Everaers, Ralf

    2010-01-01

    We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements and into the t...

  1. Can Text Messages Mitigate Summer Melt?

    Science.gov (United States)

    Castleman, Benjamin L.; Page, Lindsay C.

    2013-01-01

    Higher education officials have long been familiar with the concept of "summer melt," where students who have paid a deposit to attend one college or university instead matriculate at a different institution, usually presumed to be of comparable quality. In previous research, drawing on longitudinal data from various urban school…

  2. Radiation polymerized hot melt pressure sensitive adhesives

    International Nuclear Information System (INIS)

    Pastor, S.D.; Skoultchi, M.M.

    1977-01-01

    Hot melt pressure sensitive adhesive compositions formed by copolymerizing at least one 3-(chlorinated aryloxy)-2-hydroxypropyl ester of an alpha, beta unsaturated carboxylic acid with acrylate based copolymerizable monomers, are described. The resultant ethylenically saturated prepolymer is heated to a temperature sufficient to render it fluid and flowable. This composition is coated onto a substrate and exposed to ultraviolet radiation

  3. Catastrophic failure of polymer melts during extension

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.

    2013-01-01

    Numerical flow modeling has been applied to study the break of monodisperse polymer melts during extension. These continuum mechanical based computations are within the ideas of the microstructural ’interchain pressure’ theory. Calculated breaks, a result of small initial sample imperfections, ag...

  4. Pressure-Induced Melting of Confined Ice

    NARCIS (Netherlands)

    Sotthewes, Kai; Bampoulis, Pantelis; Zandvliet, Henricus J.W.; Lohse, Detlef; Poelsema, B.

    2017-01-01

    The classic regelation experiment of Thomson in the 1850s deals with cutting an ice cube, followed by refreezing. The cutting was attributed to pressure-induced melting but has been challenged continuously, and only lately consensus emerged by understanding that compression shortens the O:H nonbond

  5. Melting Metal on a Playing Card

    Science.gov (United States)

    Greenslade, Thomas B., Jr.

    2016-01-01

    Many of us are familiar with the demonstration of boiling water in a paper cup held over a candle or a Bunsen burner; the ignition temperature of paper is above the temperature of 100°C at which water boils under standard conditions. A more dramatic demonstration is melting tin held in a playing card. This illustration is from Tissandier's book on…

  6. Needleless Melt-Electrospinning of Polypropylene Nanofibres

    Directory of Open Access Journals (Sweden)

    Jian Fang

    2012-01-01

    Full Text Available Polypropylene (PP nanofibres have been electrospun from molten PP using a needleless melt-electrospinning setup containing a rotary metal disc spinneret. The influence of the disc spinneret (e.g., disc material and diameter, operating parameters (e.g., applied voltage, spinning distance, and a cationic surfactant on the fibre formation and average fibre diameter were examined. It was shown that the metal material used for making the disc spinneret had a significant effect on the fibre formation. Although the applied voltage had little effect on the fibre diameter, the spinning distance affected the fibre diameter considerably, with shorter spinning distance resulting in finer fibres. When a small amount of cationic surfactant (dodecyl trimethyl ammonium bromide was added to the PP melt for melt-electrospinning, the fibre diameter was reduced considerably. The finest fibres produced from this system were 400±290 nm. This novel melt-electrospinning setup may provide a continuous and efficient method to produce PP nanofibres.

  7. Multicomponent Diffusion in Experimentally Cooled Melt Inclusions

    Science.gov (United States)

    Saper, L.; Stolper, E.

    2017-12-01

    Glassy olivine-hosted melt inclusions are compositionally zoned, characterized by a boundary layer depleted in olivine-compatible components that extends into the melt inclusion from its wall. The boundary layer forms in response to crystallization of olivine and relaxes with time due to diffusive exchange with the interior of the inclusion. At magmatic temperatures, the time scale for homogenization of inclusions is minutes to hours. Preservation of compositional gradients in natural inclusions results from rapid cooling upon eruption. A model of MgO concentration profiles that couples crystal growth and diffusive relaxation of a boundary layer can be used to solve for eruptive cooling rates [1]. Controlled cooling-rate experiments were conducted to test the accuracy of the model. Mauna Loa olivine containing >80 µm melt inclusions were equilibrated at 1225°C in a 1-atm furnace for 24 hours, followed by linear cooling at rates of 102 - 105 °C/hr. High-resolution concentration profiles of 40 inclusions were obtained using an electron microprobe. The model of [1] fits the experimental data with low residuals and the best-fit cooling rates are within 30% of experimental values. The initial temperature of 1225 °C is underestimated by 65°C. The model was modified using (i) MELTS to calculate the interface melt composition as a function of temperature, and (ii) a concentration-dependent MgO diffusion coefficient using the functional form of [2]. With this calibration the best-fit starting temperatures are within 5°C of the experimental values and the best-fit cooling rates are within 20% of experimental rates. The evolution of the CaO profile during cooling is evidence for strong diffusive coupling between melt components. Because CaO is incompatible in olivine, CaO concentrations are expected to be elevated in the boundary layer adjacent to the growing olivine. Although this is observed at short time scales, as the profile evolves the CaO concentration near the

  8. Address Points - Allegheny County Address Points 201601

    Data.gov (United States)

    NSGIC Education | GIS Inventory — This dataset contains Address Points in Allegheny County. The Address Points were created by GDR for the Allegheny County CAD project, October 2008. Data is updated...

  9. Cold crucible levitation melting of biomedical Ti-30 wt%Ta alloy.

    Science.gov (United States)

    Fukui, H; Yang, W; Yamada, S; Fujishiro, Y; Morita, A; Niinomi, M

    2001-06-01

    Recently, titanium-tantalum alloys have been studied as implant materials for dental and orthopedic surgery. However, titanium and tantalum are difficult to mix by common arc melting and induction melting, because of their high melting point and the marked difference between their densities (Ti: 1,680 degrees C, 4.5 g/cm3, Ta: 2,990 degrees C, 16.6 g/cm3). Thus, the Cold Crucible Levitation Melting (CCLM) method was chosen to produce a Ti-30 wt%Ta binary alloy in the present study. The CCLM furnace, with 1 kg capacity, consisted of a water-cooled crucible comprising oxygen-free high purity copper segments and coils wrapped around the crucible and connected to a frequency inverter power supply. A qualified ingot of 1.0 kg of Ti-30 wt%Ta alloy was obtained. The ingot was characterized from the surface quality, chemical composition distribution and microstructure, and finally the melting process was discussed.

  10. Molecular dynamics for near melting temperatures simulations of metals using modified embedded-atom method

    Science.gov (United States)

    Etesami, S. Alireza; Asadi, Ebrahim

    2018-01-01

    Availability of a reliable interatomic potential is one of the major challenges in utilizing molecular dynamics (MD) for simulations of metals at near the melting temperatures and melting point (MP). Here, we propose a novel approach to address this challenge in the concept of modified-embedded-atom (MEAM) interatomic potential; also, we apply the approach on iron, nickel, copper, and aluminum as case studies. We propose adding experimentally available high temperature elastic constants and MP of the element to the list of typical low temperature properties used for the development of MD interatomic potential parameters. We show that the proposed approach results in a reasonable agreement between the MD calculations of melting properties such as latent heat, expansion in melting, liquid structure factor, and solid-liquid interface stiffness and their experimental/computational counterparts. Then, we present the physical properties of mentioned elements near melting temperatures using the new MEAM parameters. We observe that the behavior of elastic constants, heat capacity and thermal linear expansion coefficient at room temperature compared to MP follows an empirical linear relation (α±β × MP) for transition metals. Furthermore, a linear relation between the tetragonal shear modulus and the enthalpy change from room temperature to MP is observed for face-centered cubic materials.

  11. Investigation of transient melting of tungsten by ELMs in ASDEX Upgrade

    Science.gov (United States)

    Krieger, K.; Sieglin, B.; Balden, M.; Coenen, J. W.; Göths, B.; Laggner, F.; de Marne, P.; Matthews, G. F.; Nille, D.; Rohde, V.; Dejarnac, R.; Faitsch, M.; Giannone, L.; Herrmann, A.; Horacek, J.; Komm, M.; Pitts, R. A.; Ratynskaia, S.; Thoren, E.; Tolias, P.; ASDEX-Upgrade Team; EUROfusion MST1 Team

    2017-12-01

    Repetitive melting of tungsten by power transients originating from edge localized modes (ELMs) has been studied in the tokamak experiment ASDEX Upgrade. Tungsten samples were exposed to H-mode discharges at the outer divertor target plate using the Divertor Manipulator II system. The exposed sample was designed with an elevated sloped surface inclined against the incident magnetic field to increase the projected parallel power flux to a level were transient melting by ELMs would occur. Sample exposure was controlled by moving the outer strike point to the sample location. As extension to previous melt studies in the new experiment both the current flow from the sample to vessel potential and the local surface temperature were measured with sufficient time resolution to resolve individual ELMs. The experiment provided for the first time a direct link of current flow and surface temperature during transient ELM events. This allows to further constrain the MEMOS melt motion code predictions and to improve the validation of its underlying model assumptions. Post exposure ex situ analysis of the retrieved samples confirms the decreased melt motion observed at shallower magnetic field line to surface angles compared to that at leading edges exposed to the parallel power flux.

  12. Study of Using Solar Thermal Power for the Margarine Melting Heat Process.

    Science.gov (United States)

    Sharaf Eldean, Mohamed A; Soliman, A M

    2015-04-01

    The heating process of melting margarine requires a vast amount of thermal energy due to its high melting point and the size of the reservoir it is contained in. Existing methods to heat margarine have a high hourly cost of production and use fossil fuels which have been shown to have a negative impact on the environment. Thus, we perform an analytical feasibility study of using solar thermal power as an alternative energy source for the margarine melting process. In this study, the efficiency and cost effectiveness of a parabolic trough collector (PTC) solar field are compared with that of a steam boiler. Different working fluids (water vapor and Therminol-VP1 heat transfer oil (HTO)) through the solar field are also investigated. The results reveal the total hourly cost ($/h) by the conventional configuration is much greater than the solar applications regardless of the type of working fluid. Moreover, the conventional configuration causes a negative impact to the environment by increasing the amount of CO 2 , CO, and NO 2 by 117.4 kg/day, 184 kg/day, and 74.7 kg/day, respectively. Optimized period of melt and tank volume parameters at temperature differences not exceeding 25 °C are found to be 8-10 h and 100 m 3 , respectively. The solar PTC operated with water and steam as the working fluid is recommended as a vital alternative for the margarine melting heating process.

  13. Focused ion beam structuring of low melting polymeric materials

    International Nuclear Information System (INIS)

    Schmied, R.

    2014-01-01

    This thesis focuses on heating effects during focused ion beam (FIB) processing of low melting polymers. The combined approach using experiments and simulations identifies the in part massive local temperatures as a convolution between intrinsic ion-matter effects and a considerable, technically-induced heating component. While the former is invariable, the latter has been minimized by an alternative process strategy which massively improves the morphological stability and minimizes chemical damage during FIB processing, thus opening new possibilities for application on sensitive, low melting materials. The study starts with systematic experimental investigations which strongly suggested the existence of a technically-induced heating component as a consequence of classically-used serpentine or raster-like patterning strategies. Based on these results, a combined simulation approach of ion trajectories and thermal spike model calculations have been employed to get a deeper insight into spatial and temporal temperature evolution. The results were then combined with the thermodynamic behavior of polymers by means of melting and volatizing temperatures. The comparison of these simulationbased predictions with real FIB experiments revealed very good agreement, proving the applicability of the approach used to describe the temperature evolution from a fundamental point of view. As a next step, these simulations were then applied to the dierent scanning strategies which further con rmed the existence of a technically-induced heating component via classically-used patterning approaches. Due to the deep insight gained via simulations, an alternative patterning strategy was developed, which was expected to minimize these avoidable influences. This new strategy was then evaluated using a multi-technique approach, which revealed strongly reduced chemical damage together with increasing morphological stabilities even for temperature-sensitive polymers. Finally, this alternative

  14. Shallow mantle melt stagnation under Gakkel Ridge

    Science.gov (United States)

    von der Handt, A.; Snow, J. E.; Hellebrand, E.; Dick, H. J. B.; Michael, P.

    2003-04-01

    Few studies have been devoted to abyssal plagioclase peridotites, despite their relatively high abundance (30% of AP). Their origin is still unresolved, probably because intense alteration sets limits to spatially controlled geochemical analysis and obliterates textural relationships. Impregnation by a melt is the most widely accepted theory whereas other studies propose an origin by retrogression from spinel to plagioclase facies conditions. During the AMORE cruise along Gakkel Ridge in summer 2001, a dredge haul recovered spinel and plagioclase lherzolites in the axial valley of the amagmatic area. Their exceptional freshness has allowed to analyse all mineral phases. Plagioclase-bearing and -free samples are coarse-grained cpx-rich lherzolites. The plagioclase lherzolites show a wide range of modal plagioclase-contents and often showes textures related to impregnation. Noticeable are the common symplectite textures in the plagioclase peridotites, mostly opx-plag around cpx grains but also one ol-plag around cpx, suggesting a breakdown origin. The spinel lherzolites are characterised by low spinel-Cr# (˜16) and homogeneous flat cpx REE-patterns (~6 x CI). The plagioclase peridotites display strong compositional heterogeneities with pronounced core-rim variations in major and trace elements. Trace element variations in cpx show consistent correlations with textures as contact with plagioclase or symplectite formation. The An-contents of plagioclase range from 76 to 94, spinel Cr# from 10 to 48. Plagioclase trace element data reveal low concentrations for the LREE and no positive Sr-anomaly. Therefore it suggests an impregnation origin for most of the plagioclase by an already fractionated and depleted melt. Yet a minor breakdown component can be observed which was probably triggered by the impregnation. The inferred composition of this melt cannot be correlated with the nearest basalts in this region nor with a melt produced by melting of the spinel lherzolites.

  15. Local and bulk melting of Cu at grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Shengnian [Los Alamos National Laboratory; Han, Li - Bo [USTC; An, Qi [USTC/CALTECH; Fu, Rong - Shan [USTC; Zheng, Lianqing [FSU

    2008-01-01

    We investigate gain boundary (GB) melting using molecular dynamics simulations on face-centered-cubic Cu bicrystals with symmetric {l_angle}110{r_angle} tilt grain boundaries. Two representative types of GBs are explored: {Sigma} = 11/(113)/50.48{sup o} (low GB energy) and {Sigma} = 27/(552)/148.41{sup o} (high GB energy). The temperature and temporal evolutions of the Cu bicrystals under stepped heating are characterized in terms of order parameters and diffusion coefficients, as ell as the nucleation and growth of melt. Within the GB region, continuous local melting precedes discontinuous bulk melting, while continuous solid state disordering may precede local melting. Premelting may occur for local melting but not for bulk melting. For {Sigma} = 11/(113)/50.48{sup o}, premelting of the GB region is negligible, and local melting occurs near the thermodynamic melting temperature. The GB region as a whole is superheated by about 13% before its bulk melting. In the case of {Sigma} = 27/(552)/148.41, considerable premelting is observed for local melting, while the bulk melting occurs with negligible superheating. The exact melting behavior of a general GB depends on the GB energy, but is likely bracketed within these two cases.

  16. The influence of partial melting and melt migration on the rheology of the continental crust

    Science.gov (United States)

    Cavalcante, Geane Carolina G.; Viegas, Gustavo; Archanjo, Carlos José; da Silva, Marcos Egydio

    2016-11-01

    The presence of melt during deformation produces a drastic change in the rheological behavior of the continental crust; rock strength is decreased even for melt fractions as low as ∼7%. At pressure/temperature conditions typical of the middle to lower crust, melt-bearing systems may play a critical role in the process of strain localization and in the overall strength of the continental lithosphere. In this contribution we focus on the role and dynamics of melt flow in two different mid-crustal settings formed during the Brasiliano orogeny: (i) a large-scale anatectic layer in an orthogonal collision belt, represented by the Carlos Chagas anatexite in southeastern Brazil, and (ii) a strike-slip setting, in which the Espinho Branco anatexite in the Patos shear zone (northeast Brazil) serves as an analogue. Both settings, located in eastern Brazil, are part of the Neoproterozoic tectonics that resulted in widespread partial melting, shear zone development and the exhumation of middle to lower crustal layers. These layers consist of compositionally heterogeneous anatexites, with variable former melt fractions and leucosome structures. The leucosomes usually form thick interconnected networks of magma that reflect a high melt content (>30%) during deformation. From a comparison of previous work based on detailed petrostructural and AMS studies of the anatexites exposed in these areas, we discuss the rheological implications caused by the accumulation of a large volume of melt ;trapped; in mid-crustal levels, and by the efficient melt extraction along steep shear zones. Our analyses suggest that rocks undergoing partial melting along shear settings exhibit layers with contrasting competence, implying successive periods of weakening and strengthening. In contrast, regions where a large amount of magma accumulates lack clear evidence of competence contrast between layers, indicating that they experienced only one major stage of dramatic strength drop. This comparative

  17. Evaporative Heat Transfer Mechanisms within a Heat Melt Compactor

    Science.gov (United States)

    Golliher, Eric L.; Gotti, Daniel J.; Rymut, Joseph Edward; Nguyen, Brian K; Owens, Jay C.; Pace, Gregory S.; Fisher, John W.; Hong, Andrew E.

    2013-01-01

    This paper will discuss the status of microgravity analysis and testing for the development of a Heat Melt Compactor (HMC). Since fluids behave completely differently in microgravity, the evaporation process for the HMC is expected to be different than in 1-g. A thermal model is developed to support the design and operation of the HMC. Also, low-gravity aircraft flight data is described to assess the point at which water may be squeezed out of the HMC during microgravity operation. For optimum heat transfer operation of the HMC, the compaction process should stop prior to any water exiting the HMC, but nevertheless seek to compact as much as possible to cause high heat transfer and therefore shorter evaporation times.

  18. Investigation on contact melting of Cu/Al laminated composite

    Energy Technology Data Exchange (ETDEWEB)

    Pronicheva, D.V.; Gurevicha, L.M.; Trykova, Y.P.; Trunov, M.D.

    2016-07-01

    The study presents investigation of chemical composition, microhardness and electrical conductivity of Cu/Al laminated metal composite after heat treatment at temperatures higher than Cu–Al eutectic melting point. The Cu/Al bimetal was obtained via explosion welding. Chemical composition of the material after heat treatments was identified using EDS analysis. Eddy current testing was applied to investigate electrical conductivity of the composite’s components. Strain-hardened zones were identified in the explosion welded composite. The experimental value of electrical conductivity of explosion welded composite was in good coherence with calculated by additivity rule results. Heat treatments resulted in the formation of multiple interlayers which had high microhardness value and had intermetallics in composition. The electrical conductivity of the identified interlayers was significantly lower than of Cu and Al. (Author)

  19. Can Nano-Particle Melt below the Melting Temperature of Its Free Surface Partner?

    International Nuclear Information System (INIS)

    Sui Xiao-Hong; Qin Shao-Jing; Wang Zong-Guo; Kang Kai; Wang Chui-Lin

    2015-01-01

    The phonon thermal contribution to the melting temperature of nano-particles is inspected. The discrete summation of phonon states and its corresponding integration form as an approximation for a nano-particle or for a bulk system have been analyzed. The discrete phonon energy levels of pure size effect and the wave-vector shifts of boundary conditions are investigated in detail. Unlike in macroscopic thermodynamics, the integration volume of zero-mode of phonon for a nano-particle is not zero, and it plays an important role in pure size effect and boundary condition effect. We find that a nano-particle will have a rising melting temperature due to purely finite size effect; a lower melting temperature bound exists for a nano-particle in various environments, and the melting temperature of a nano-particle with free boundary condition reaches this lower bound. We suggest an easy procedure to estimation the melting temperature, in which the zero-mode contribution will be excluded, and only several bulk quantities will be used as input. We would like to emphasize that the quantum effect of discrete energy levels in nano-particles, which is not present in early thermodynamic studies on finite size corrections to melting temperature in small systems, should be included in future researches. (condensed matter: structural, mechanical, and thermal properties)

  20. Sea Ice Melt Pond Data from the Canadian Arctic

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains observations of albedo, depth, and physical characteristics of melt ponds on sea ice, taken during the summer of 1994. The melt ponds studied...

  1. Improved procedures for separating crystals from the melt

    NARCIS (Netherlands)

    Verdoes, D.; Arkenbout, G.J.; Bruinsma, O.S.L.; Koutsoukos, P.G.; Ulrich, J.

    1997-01-01

    Innovative separation techniques like melt crystallization have the potential to fulfil two important demands, namely: a significant reduction of energy consumption by the chemical industry, and the production of high quality products required by industry. Several industrial applications of melt

  2. Causes of Glacier Melt Extremes in the Alps Since 1949

    Science.gov (United States)

    Thibert, E.; Dkengne Sielenou, P.; Vionnet, V.; Eckert, N.; Vincent, C.

    2018-01-01

    Recent record-breaking glacier melt values are attributable to peculiar extreme events and long-term warming trends that shift averages upward. Analyzing one of the world's longest mass balance series with extreme value statistics, we show that detrending melt anomalies makes it possible to disentangle these effects, leading to a fairer evaluation of the return period of melt extreme values such as 2003, and to characterize them by a more realistic bounded behavior. Using surface energy balance simulations, we show that three independent drivers control melt: global radiation, latent heat, and the amount of snow at the beginning of the melting season. Extremes are governed by large deviations in global radiation combined with sensible heat. Long-term trends are driven by the lengthening of melt duration due to earlier and longer-lasting melting of ice along with melt intensification caused by trends in long-wave irradiance and latent heat due to higher air moisture.

  3. Students' Understanding of Boiling Points and Intermolecular Forces

    Science.gov (United States)

    Schmidt, Hans-Jurgen; Kaufmann, Birgit; Treagust, David F.

    2009-01-01

    In introductory chemistry courses students are presented with the model that matter is composed of particles, and that weak forces of attraction exist between them. This model is used to interpret phenomena such as solubility and melting points, and aids in understanding the changes in states of matter as opposed to chemical reactions. We…

  4. Efficient approach to compute melting properties fully from ab initio with application to Cu

    Science.gov (United States)

    Zhu, Li-Fang; Grabowski, Blazej; Neugebauer, Jörg

    2017-12-01

    Applying thermodynamic integration within an ab initio-based free-energy approach is a state-of-the-art method to calculate melting points of materials. However, the high computational cost and the reliance on a good reference system for calculating the liquid free energy have so far hindered a general application. To overcome these challenges, we propose the two-optimized references thermodynamic integration using Langevin dynamics (TOR-TILD) method in this work by extending the two-stage upsampled thermodynamic integration using Langevin dynamics (TU-TILD) method, which has been originally developed to obtain anharmonic free energies of solids, to the calculation of liquid free energies. The core idea of TOR-TILD is to fit two empirical potentials to the energies from density functional theory based molecular dynamics runs for the solid and the liquid phase and to use these potentials as reference systems for thermodynamic integration. Because the empirical potentials closely reproduce the ab initio system in the relevant part of the phase space the convergence of the thermodynamic integration is very rapid. Therefore, the proposed approach improves significantly the computational efficiency while preserving the required accuracy. As a test case, we apply TOR-TILD to fcc Cu computing not only the melting point but various other melting properties, such as the entropy and enthalpy of fusion and the volume change upon melting. The generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional and the local-density approximation (LDA) are used. Using both functionals gives a reliable ab initio confidence interval for the melting point, the enthalpy of fusion, and entropy of fusion.

  5. A 2D double-porosity model for melting and melt migration beneath mid-oceanic ridges

    Science.gov (United States)

    Liu, B.; Liang, Y.; Parmentier, E.

    2017-12-01

    Several lines of evidence suggest that the melting and melt extraction region of the MORB mantle is heterogeneous consisting of an interconnected network of high permeability dunite channels in a low porosity harzburgite or lherzolite matrix. In principle, one can include channel formation into the tectonic-scale geodynamic models by solving conservation equations for a chemically reactive and viscously deformable porous medium. Such an approach eventually runs into computational limitations such as resolving fractal-like channels that have a spectrum of width. To better understand first order features of melting and melt-rock interaction beneath MOR, we have formulated a 2D double porosity model in which we treat the triangular melting region as two overlapping continua occupied by the low-porosity matrix and interconnected high-porosity channels. We use melt productivity derived from a thermodynamic model and melt suction rate to close our problem. We use a high-order accurate numerical method to solve the conservation equations in 2D for porosity, solid and melt velocities and concentrations of chemical tracers in the melting region. We carry out numerical simulations to systematically study effects of matrix-to-channel melt suction and spatially distributed channels on the distributions of porosity and trace element and isotopic ratios in the melting region. For near fractional melting with 10 vol% channel in the melting region, the flow field of the matrix melt follows closely to that of the solid because the small porosity (exchange between the melt and the solid. The smearing effect can be approximated by dispersion coefficient. For slowly diffusing trace elements (e.g., LREE and HFSE), the melt migration induced dispersion can be as effective as thermal diffusion. Therefore, sub-kilometer scale heterogeneities of Nd and Hf isotopes are significantly damped or homogenized in the melting region.

  6. Electrochemistry of silicon in chloro-fluoride and carbonate melts

    Directory of Open Access Journals (Sweden)

    Devyatkin S.V.

    2003-01-01

    Full Text Available The electrochemical behavior of K2SiF6 in chloro-fluoride melts and that of SiO2 in carbonate melts has been studied. Silicon, titanium silicides, boron silicide and ternary compounds Ti-Si-B have been deposited from chloro-fluoride melts. Only SiC was deposited from carbonate-silica melts under carbon dioxide atmosphere (that is, excessive pressure of CO2.

  7. Nanoparticle-induced unusual melting and solidification behaviours of metals

    OpenAIRE

    Ma, Chao; Chen, Lianyi; Cao, Chezheng; Li, Xiaochun

    2017-01-01

    Effective control of melting and solidification behaviours of materials is significant for numerous applications. It has been a long-standing challenge to increase the melted zone (MZ) depth while shrinking the heat-affected zone (HAZ) size during local melting and solidification of materials. In this paper, nanoparticle-induced unusual melting and solidification behaviours of metals are reported that effectively solve this long-time dilemma. By introduction of Al2O3 nanoparticles, the MZ dep...

  8. Investigating the vortex melting phenomenon in BSCCO crystals ...

    Indian Academy of Sciences (India)

    To study the fluctuations in the local melting temperature/field, we have constructed maps of the melting landscape m(, ), viz., the melting temperature (m) at ... Department of Condensed Matter Physics, The Weizmann Institute of Science, Rehovot 76100, Israel; Department of Applied Physics, The University of Tokyo, ...

  9. Melt flow characteristics in gas-assisted laser cutting

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Abstract. We present a study on laser cutting of mild steel with oxygen as an assist gas. We correlate the cut surface quality with the melt film thickness. We estimate the optimum pressure required for melt ejection under laminar flow regime. The thickness of melt film inside the kerf is estimated using mass balance and the ...

  10. Investigation of the stability of melt flow in gating systems

    DEFF Research Database (Denmark)

    Tiedje, Niels Skat; Larsen, Per

    2011-01-01

    Melt flow in four different gating systems designed for production of brake discs was analysed experimentally and by numerical modelling. In the experiments moulds were fitted with glass fronts and melt flow was recorded on video. The video recordings were compared with modelling of melt flow in ...

  11. Elongational viscosity of monodisperse and bidisperse polystyrene melts

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole

    2006-01-01

    The start-up and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 and 103 kg/mole, and for three bidisperse polystyrene melts. The monodisperse melts show a maximum in the steady elongational viscosity vs. the elongational...

  12. Melt pool vorticity in deep penetration laser material welding

    Indian Academy of Sciences (India)

    this value, convective heat transfer indicates melting and evaporation occurring in the weld pool during laser ... while surface tension and hydrostatic pressure help to retain the melt in the keyhole cavity in this high .... so does the strength of the shock wave and the Mach angle becomes increasingly narrow. As the melt flow ...

  13. Melting of metallic intermediate level waste

    International Nuclear Information System (INIS)

    Huutoniemi, Tommi; Larsson, Arne; Blank, Eva

    2013-08-01

    This report presents a feasibility study of a melting facility for core components and reactor internals. An overview is given of how such a facility for treatment of intermediate level waste might be designed, constructed and operated and highlights both the possibilities and challenges. A cost estimate and a risk analysis are presented in order to make a conclusion of the technical feasibility of such a facility. Based on the authors' experience in operating a low level waste melting facility, their conclusion is that without technical improvements such a facility is not feasible today. This is based on the cost of constructing and operating such a facility, in conjunction with the radiological risks associated with operation and the uncertain benefits to disposal and long term safety

  14. Detection of structural heterogeneity of glass melts

    DEFF Research Database (Denmark)

    Yue, Yuanzheng

    2004-01-01

    The structural heterogeneity of both supercooled liquid and molten states of silicate has been studied using calorimetric method. The objects of this study are basaltic glasses and liquids. Two experimental approaches are taken to detect the structural heterogeneity of the liquids. One...... is discussed. The ordered structure of glass melts above the liquidus temperature is indirectly characterized by use of X-ray diffraction method. The new approaches are of importance for monitoring the glass melting and forming process and for improving the physical properties of glasses and glass fibers....... is the hyperquench-anneal-calorimetric scan approach, by which the structural information of a basaltic supercooled liquid and three binary silicate liquids is acquired. Another is the calorimetrically repeated up- and downscanning approach, by which the structural heterogeneity, the intermediate range order...

  15. Melting of metallic intermediate level waste

    Energy Technology Data Exchange (ETDEWEB)

    Huutoniemi, Tommi; Larsson, Arne; Blank, Eva [Studsvik Nuclear AB, Nykoeping (Sweden)

    2013-08-15

    This report presents a feasibility study of a melting facility for core components and reactor internals. An overview is given of how such a facility for treatment of intermediate level waste might be designed, constructed and operated and highlights both the possibilities and challenges. A cost estimate and a risk analysis are presented in order to make a conclusion of the technical feasibility of such a facility. Based on the authors' experience in operating a low level waste melting facility, their conclusion is that without technical improvements such a facility is not feasible today. This is based on the cost of constructing and operating such a facility, in conjunction with the radiological risks associated with operation and the uncertain benefits to disposal and long term safety.

  16. Stress Relaxation in Entangled Polymer Melts

    DEFF Research Database (Denmark)

    Hou, Ji-Xuan; Svaneborg, Carsten; Everaers, Ralf

    2010-01-01

    We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements and into the t......We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements...... excellent agreement for the Likhtman-McLeish theory using the double reptation approximation for constraint release, if we remove the contribution of high-frequency modes to contour length fluctuations of the primitive chain....

  17. Shock-induced melting in anorthositic rock 60015 and a fragment of anorthositic breccia from the 'picking pot' /70052/. [meteoritic impacts on moon

    Science.gov (United States)

    Sclar, C. B.; Bauer, J. F.

    1974-01-01

    Microscopic and chemical evidence are presented to support the contention that shock-generated incipient grain-boundary melting of plagioclase occurred in an anorthositic lunar rock and that shock-generated plagioclase liquid was present along grain boundaries during post-shock adiabatic expansion in a fragment of anorthositic breccia. The first contention is supported by microtextural relationships in the rock, the composition of its metal particles (most iron with some cobalt and less nickel), and glass inclusions with vapor bubbles. The second contention is supported by angular irregular voids in the fragment as well as the occurrence of oriented glass filaments in some of the voids. It is shown that shock-generation of 'cataclastic anorthosite' and high-temperature plagioclase liquids can explain the exceptionally young lead and argon ages of the anorthositic rock. The results of the breccia study indicate that shock lithification of plagioclase-rich particulate material from the highland regolith is due to grain-boundary melting of plagioclase.

  18. BWR core melt progression phenomena: Experimental analyses

    International Nuclear Information System (INIS)

    Ott, L.J.

    1992-01-01

    In the BWR Core Melt in Progression Phenomena Program, experimental results concerning severe fuel damage and core melt progression in BWR core geometry are used to evaluate existing models of the governing phenomena. These include control blade eutectic liquefaction and the subsequent relocation and attack on the channel box structure; oxidation heating and hydrogen generation; Zircaloy melting and relocation; and the continuing oxidation of zirconium with metallic blockage formation. Integral data have been obtained from the BWR DF-4 experiment in the ACRR and from BWR tests in the German CORA exreactor fuel-damage test facility. Additional integral data will be obtained from new CORA BWR test, the full-length FLHT-6 BWR test in the NRU test reactor, and the new program of exreactor experiments at Sandia National Laboratories (SNL) on metallic melt relocation and blockage formation. an essential part of this activity is interpretation and use of the results of the BWR tests. The Oak Ridge National Laboratory (ORNL) has developed experiment-specific models for analysis of the BWR experiments; to date, these models have permitted far more precise analyses of the conditions in these experiments than has previously been available. These analyses have provided a basis for more accurate interpretation of the phenomena that the experiments are intended to investigate. The results of posttest analyses of BWR experiments are discussed and significant findings from these analyses are explained. The ORNL control blade/canister models with materials interaction, relocation and blockage models are currently being implemented in SCDAP/RELAP5 as an optional structural component

  19. In vessel core melt progression phenomena

    International Nuclear Information System (INIS)

    Courtaud, M.

    1993-01-01

    For all light water reactor (LWR) accidents, including the so called severe accidents where core melt down can occur, it is necessary to determine the amount and characteristics of fission products released to the environment. For existing reactors this knowledge is used to evaluate the consequences and eventual emergency plans. But for future reactors safety authorities demand decrease risks and reactors designed in such a way that fission products are retained inside the containment, the last protective barrier. This requires improved understanding and knowledge of all accident sequences. In particular it is necessary to be able to describe the very complex phenomena occurring during in vessel core melt progression because they will determine the thermal and mechanical loads on the primary circuit and the timing of its rupture as well as the fission product source term. On the other hand, in case of vessel failure, knowledge of the physical and chemical state of the core melt will provide the initial conditions for analysis of ex-vessel core melt progression and phenomena threatening the containment. Finally a good understanding of in vessel phenomena will help to improve accident management procedures like Emergency Core Cooling System water injection, blowdown and flooding of the vessel well, with their possible adverse effects. Research and Development work on this subject was initiated a long time ago and is still in progress but now it must be intensified in order to meet the safety requirements of the next generation of reactors. Experiments, limited in scale, analysis of the TMI 2 accident which is a unique source of global information and engineering judgment are used to establish and assess physical models that can be implemented in computer codes for reactor accident analysis

  20. Conditioning of nuclear cladding wastes by melting

    International Nuclear Information System (INIS)

    Puyou, M.; Jouan, A.; Jacquet-Francillon, N.

    1991-01-01

    This paper discusses a cold-crucible induction melting process to condition cladding waste from irradiated fast breeder reactor fuel. The process has been developed by the CEA at Marcoule (France) as part of a major R and D program. It has been qualified at industrial scale on nonradioactive waste, and at laboratory scale on radioactive waste: several radioactive ingots have been produced from actual stainless steel or zircaloy hulls. The results confirm the numerous advantages of this containment method

  1. Holographic picture of heavy vector meson melting

    Energy Technology Data Exchange (ETDEWEB)

    Braga, Nelson R.F.; Diles, Saulo [Universidade Federal do Rio de Janeiro, Instituto de Fisica, Rio de Janeiro, RJ (Brazil); Martin Contreras, Miguel Angel [Universidad de los Andes, High Energy Group, Department of Physics, Bogota (Colombia)

    2016-11-15

    The fraction of heavy vector mesons produced in a heavy ion collision, as compared to a proton-proton collision, serves as an important indication of the formation of a thermal medium, the quark-gluon plasma. This sort of analysis strongly depends on understanding the thermal effects of a medium like the plasma on the states of heavy mesons. In particular, it is crucial to know the temperature ranges where they undergo a thermal dissociation, or melting. AdS/QCD models are know to provide an important tool for the calculation of hadronic masses, but in general are not consistent with the observation that decay constants of heavy vector mesons decrease with excitation level. It has recently been shown that this problem can be overcome using a soft wall background and introducing an extra energy parameter, through the calculation of correlation functions at a finite position of anti-de Sitter space. This approach leads to the evaluation of masses and decay constants of S wave quarkonium states with just one flavor dependent and one flavor independent parameter. Here we extend this more realistic model to finite temperatures and analyze the thermal behavior of the states 1S, 2S and 3S of bottomonium and charmonium. The corresponding spectral function exhibits a consistent picture for the melting of the states where, for each flavor, the higher excitations melt at lower temperatures. We estimate for these six states the energy ranges in which the heavy vector mesons undergo a transition from a well-defined peak in the spectral function to complete melting in the thermal medium. A very clear distinction between the heavy flavors emerges, with the bottomonium state Υ(1S) surviving a deconfinement transition at temperatures much larger than the critical deconfinement temperature of the medium. (orig.)

  2. The electrical conductivity of sodium polysulfide melts

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Meihui [Univ. of California, Berkeley, CA (United States)

    1992-06-01

    The sodium polysulfide melt has been described by a macroscopic model. This model considers the melt to be composed of sodium cations, monosulfide anions, and neutral sulfur solvent. The transport equations of concentrated-solution theory are used to derived the governing equations for this binaryelectrolyte melt model. These equations relate measurable transport properties to fundamental transport parameters. The focus of this research is to measure the electrical conductivity of sodium polysulfide melts and calculate one of fundamental transport parameters from the experimental data. The conductance cells used in the conductivity measurements are axisymmetric cylindrical cells with a microelectrode. The electrode effects, including double-layer capacity, charge transfer resistance, and concentration overpotential, were minimized by the use of the alternating current at an adequately high frequency. The high cell constants of the conductance cells not only enhanced the experimental accuracy but also made the electrode effects negligible. The electrical conductivities of sodium polysulfide Na2S4 and Na2S5 were measured as a function of temperature (range: 300 to 360°C). Variations between experiments were only up to 2%. The values of the Arrhenius activation energy derived from the experimental data are about 33 kJ/mol. The fundamental transport parameter which quantifies the interaction within sodium cations and monosulfide anions are of interest and expected to be positive. Values of it were calculated from the experimental conductivity data and most of them are positive. Some negative values were obtained probably due to the experimental errors of transference number, diffusion coefficient, density or conductivity data.

  3. The electrical conductivity of sodium polysulfide melts

    Energy Technology Data Exchange (ETDEWEB)

    Meihui Wang.

    1992-06-01

    The sodium polysulfide melt has been described by a macroscopic model. This model considers the melt to be composed of sodium cations, monosulfide anions, and neutral sulfur solvent. The transport equations of concentrated-solution theory are used to derived the governing equations for this binaryelectrolyte melt model. These equations relate measurable transport properties to fundamental transport parameters. The focus of this research is to measure the electrical conductivity of sodium polysulfide melts and calculate one of fundamental transport parameters from the experimental data. The conductance cells used in the conductivity measurements are axisymmetric cylindrical cells with a microelectrode. The electrode effects, including double-layer capacity, charge transfer resistance, and concentration overpotential, were minimized by the use of the alternating current at an adequately high frequency. The high cell constants of the conductance cells not only enhanced the experimental accuracy but also made the electrode effects negligible. The electrical conductivities of sodium polysulfide Na{sub 2}S{sub 4} and Na{sub 2}S{sub 5} were measured as a function of temperature (range: 300 to 360{degree}C). Variations between experiments were only up to 2%. The values of the Arrhenius activation energy derived from the experimental data are about 33 kJ/mol. The fundamental transport parameter which quantifies the interaction within sodium cations and monosulfide anions are of interest and expected to be positive. Values of it were calculated from the experimental conductivity data and most of them are positive. Some negative values were obtained probably due to the experimental errors of transference number, diffusion coefficient, density or conductivity data.

  4. "Chemical contraction" in rubidium-bismuth melts

    Science.gov (United States)

    Khairulin, R. A.; Abdullaev, R. N.; Stankus, S. V.

    2017-10-01

    The density and thermal expansion of liquid rubidium and rubidium-bismuth alloy containing 25.0 at % Bi were measured by the gamma-ray attenuation technique at temperatures from liquidus to 1000 K. The results of this study were compared with the data obtained by other authors. The molar volume of the Rb75Bi25 melt strongly deviates from the additivity rule for ideal solutions.

  5. Vacuum induction melting of uranium ingots

    International Nuclear Information System (INIS)

    Hussain, M.M.; Bagchi, S.N.; Singh, S.P.

    1992-01-01

    Massive uranium ingot is produced from green salt (UF 4 ) using calciothermic reduction (CTR) or magnesiothermic reduction (MTR) process. CTR process has been replaced by MTR process at Trombay due to economic considerations. This paper highlights problems associated with the vacuum induction melting of MTR ingots and the remedial measures taken to produce good quality billets. Details of metallographic examination of inclusions in ingots and billets have been incorporated. (author). 3 figs

  6. Melts of garnet lherzolite: experiments, models and comparison to melts of pyroxenite and carbonated lherzolite

    Science.gov (United States)

    Grove, Timothy L.; Holbig, Eva S.; Barr, Jay A.; Till, Christy B.; Krawczynski, Michael J.

    2013-01-01

    Phase equilibrium experiments on a compositionally modified olivine leucitite from the Tibetan plateau have been carried out from 2.2 to 2.8 GPa and 1,380–1,480 °C. The experiments-produced liquids multiply saturated with spinel and garnet lherzolite phase assemblages (olivine, orthopyroxene, clinopyroxene and spinel ± garnet) under nominally anhydrous conditions. These SiO2-undersaturated liquids and published experimental data are utilized to develop a predictive model for garnet lherzolite melting of compositionally variable mantle under anhydrous conditions over the pressure range of 1.9–6 GPa. The model estimates the major element compositions of garnet-saturated melts for a range of mantle lherzolite compositions and predicts the conditions of the spinel to garnet lherzolite phase transition for natural peridotite compositions at above-solidus temperatures and pressures. We compare our predicted garnet lherzolite melts to those of pyroxenite and carbonated lherzolite and develop criteria for distinguishing among melts of these different source types. We also use the model in conjunction with a published predictive model for plagioclase and spinel lherzolite to characterize the differences in major element composition for melts in the plagioclase, spinel and garnet facies and develop tests to distinguish between melts of these three lherzolite facies based on major elements. The model is applied to understand the source materials and conditions of melting for high-K lavas erupted in the Tibetan plateau, basanite–nephelinite lavas erupted early in the evolution of Kilauea volcano, Hawaii, as well as younger tholeiitic to alkali lavas from Kilauea.

  7. A Novel Melt-Dispersion Technique for Simplistic Preparation of Chlorpromazine-Loaded Polycaprolactone Nanocapsules

    Directory of Open Access Journals (Sweden)

    Thiresen Govender

    2015-06-01

    Full Text Available The aim of this study was to design, synthesize and optimize chlorpromazine hydrochloride (CPZ-loaded, poly-ε-caprolactone (PCL based nanocapsules, intended for site specific delivery to the frontal lobe, using a novel melt-dispersion technique that is non-arduous, inexpensive and devoid of any hazardous organic solvents. Experimental trials using a central composite design were performed on 13 statistically derived formulations of various combinations of PCL (1000–3000 mg and Polysorbate 80 (2%–5% v/v on the physicochemical and physicomechanical properties and interactive effects on PCL nanocapsule formulation. Differential scanning calorimetry (DSC, Temperature modulated differential scanning calorimetry (TMDSC and Fourier transform infrared spectroscopy (FTIR revealed that there was no thermodegardation of the constituents utilized in the melt dispersion technique. Nanocapsule yields achieved were very high however entrapment of CPZ proved to be relatively low due to the highly hydrophilic nature of CPZ and the processing of the nanocapsules post synthesis. Nanocapsule sizes were in the nanotherapeutic range and varied from 132.7 ± 6.8 nm to 566.6 ± 5.5 nm. Zeta potential ranged from 15.1 ± 0.65 mV to 28.8 ± 0.84 mV revealing capsules that were of incipient to moderate stability. Transmission electron microscopy revealed nanocapsules that were spherical shape, well individualized with a moderate degree of flocculation. In vitro CPZ release was biphasic for all formulations with an initial burst release followed by pseudo-steady controlled release over 30 days. The cytotoxicity of the optimized nanocapsule system on a PC12 neuronal cell line proved to be minimal. Following incorporation of the optimized nanocapsules within a polymeric membrane, in vivo implantation of the device in a New Zealand Albino rabbit model proved the efficacy of the system in achieving prolonged more targeted CPZ levels to the brain. Extensive in vitro

  8. Electric melting furnace for waste solidification

    International Nuclear Information System (INIS)

    Masaki, Toshio.

    1990-01-01

    To avoid electric troubles or reduction of waste processing performance even when platinum group elements are contained in wastes to be applied with glass solidification. For this purpose, a side electrode is disposed to the side wall of a melting vessel and a central electrode serving as a counter electrode is disposed about at the center inside the melting vessel. With such a constitution, if conductive materials are deposited at the bottom of the furnace or the bottom of the melting vessel, heating currents flow selectively between the side electrode and the central electrode. Accordingly, no electric currents flow through the conductive deposits thereby enabling to prevent abnormal heating in the bottom of the furnace. Further, heat generated by electric supply between the side electrode and the central electrode is supplied efficiently to raw material on the surface of the molten glass liquid to improve the processing performance. Further, disposition of the bottom electrode at the bottom of the furnace enables current supply between the central electrode and the bottom electrode to facilitate the temperature control for the molten glass in the furnace than in the conventional structure. (I.S.)

  9. The kinetic fragility of natural silicate melts

    International Nuclear Information System (INIS)

    Giordano, Daniele; Dingwell, Donald B

    2003-01-01

    Newtonian viscosities of 19 multicomponent natural and synthetic silicate liquids, with variable contents of SiO 2 (41-79 wt%), Al 2 O 3 (10-19 wt%), TiO 2 (0-3 wt%), FeO tot (0-11 wt%); alkali oxides (5-17 wt%), alkaline-earth oxides (0-35 wt%), and minor oxides, obtained at ambient pressure using the high-temperature concentric cylinder, the low-temperature micropenetration, and the parallel plates techniques, have been analysed. For each silicate liquid, regression of the experimentally determined viscosities using the well known Vogel-Fulcher-Tammann (VFT) equation allowed the viscosity of all these silicates to be accurately described. The results of these fits, which provide the basis for the subsequent analysis here, permit qualitative and quantitative correlations to be made between the VFT adjustable parameters (A VFT , B VFT , and T 0 ). The values of B VFT and T 0 , calibrated via the VFT equation, are highly correlated. Kinetic fragility appears to be correlated with the number of non-bridging oxygens per tetrahedrally coordinated cation (NBO/T). This is taken to infer that melt polymerization controls melt fragility in liquid silicates. Thus NBO/T might form an useful ingredient of a structure-based model of non-Arrhenian viscosity in multicomponent silicate melts

  10. Melt processing of Yb-123 tapes

    International Nuclear Information System (INIS)

    Athur, S. P.; Balachandran, U.; Salama, K.

    2000-01-01

    The innovation of a simple, scalable process for manufacturing long-length conductors of HTS is essential to potential commercial applications such as power cables, magnets, and transformers. In this paper the authors demonstrate that melt processing of Yb-123 tapes made by the PIT route is an alternative to the coated conductor and Bi-2223 PIT tape fabrication techniques. Ag-clad Yb-123 tapes were fabricated by groove rolling and subsequently, melt processed in different oxygen partial pressures in a zone-melting furnace with a gradient of 140 C/cm. The transition temperatures measured were found to be around 81 K undermost processing conditions. EPMA of the tapes processed under different conditions show the 123 phase to be Ba deficient and Cu and Yb rich. Critical current was measured at various temperatures from 77 K to 4.2 K. The J c increased with decrease in pO 2 . The highest I c obtained was 52 A at 4.2 K

  11. Vortex lattice melting, pinning and kinetics

    International Nuclear Information System (INIS)

    Doniach, S.; Ryu, S.; Kapitulnik, A.

    1994-01-01

    The phenomenology of the high T c superconductors is discussed both at the level of the thermodynamics of melting of the Abrikosov flux lattice and in terms of the melting and kinetics of the flux lattice for a pinned system. The authors review results on 3D melting obtained by a Monte Carlo simulation approach in which the 2D open-quotes pancakeclose quotes vortices are treated as statistical variables. The authors discuss pinning in the context of the strong pinning regime in which the vortex density given in terms of the applied field B is small compared to that represented by an effective field B pin measuring the pinning center density. The authors introduce a new criterion for the unfreezing of a vortex glass on increase of magnetic field or temperature, in the strong pinning, small field unit. The authors model this limit in terms of a single flux line interacting with a columnar pin. This model is studied both analytically and by computer simulation. By applying a tilt potential, the authors study the kinetics of the vortex motion in an external current and show that the resulting current-voltage characteristic follows a basic vortex glass-like scaling relation in the vicinity of the depinning transition

  12. Rapid-melt Dynamic Nuclear Polarization

    Science.gov (United States)

    Sharma, M.; Janssen, G.; Leggett, J.; Kentgens, A. P. M.; van Bentum, P. J. M.

    2015-09-01

    In recent years, Dynamic Nuclear Polarization (DNP) has re-emerged as a means to ameliorate the inherent problem of low sensitivity in nuclear magnetic resonance (NMR). Here, we present a novel approach to DNP enhanced liquid-state NMR based on rapid melting of a solid hyperpolarized sample followed by 'in situ' NMR detection. This method is applicable to small (10 nl to 1 μl) sized samples in a microfluidic setup. The method combines generic DNP enhancement in the solid state with the high sensitivity of stripline 1 H NMR detection in the liquid state. Fast cycling facilitates options for signal averaging or 2D structural analysis. Preliminary tests show solid-state 1 H enhancement factors of up to 500 for H2O/D2O/d6-glycerol samples doped with TEMPOL radicals. Fast paramagnetic relaxation with nitroxide radicals, In nonpolar solvents such as toluene, we find proton enhancement factors up to 400 with negligible relaxation losses in the liquid state, using commercially available BDPA radicals. A total recycling delay (including sample freezing, DNP polarization and melting) of about 5 s can be used. The present setup allows for a fast determination of the hyper-polarization as function of the microwave frequency and power. Even at the relatively low field of 3.4 T, the method of rapid melting DNP can facilitate the detection of small quantities of molecules in the picomole regime.

  13. A 33,000-year-old incipient dog from the Altai Mountains of Siberia: evidence of the earliest domestication disrupted by the Last Glacial Maximum.

    Directory of Open Access Journals (Sweden)

    Nikolai D Ovodov

    Full Text Available BACKGROUND: Virtually all well-documented remains of early domestic dog (Canis familiaris come from the late Glacial and early Holocene periods (ca. 14,000-9000 calendar years ago, cal BP, with few putative dogs found prior to the Last Glacial Maximum (LGM, ca. 26,500-19,000 cal BP. The dearth of pre-LGM dog-like canids and incomplete state of their preservation has until now prevented an understanding of the morphological features of transitional forms between wild wolves and domesticated dogs in temporal perspective. METHODOLOGY/PRINCIPAL FINDING: We describe the well-preserved remains of a dog-like canid from the Razboinichya Cave (Altai Mountains of southern Siberia. Because of the extraordinary preservation of the material, including skull, mandibles (both sides and teeth, it was possible to conduct a complete morphological description and comparison with representative examples of pre-LGM wild wolves, modern wolves, prehistoric domesticated dogs, and early dog-like canids, using morphological criteria to distinguish between wolves and dogs. It was found that the Razboinichya Cave individual is most similar to fully domesticated dogs from Greenland (about 1000 years old, and unlike ancient and modern wolves, and putative dogs from Eliseevichi I site in central Russia. Direct AMS radiocarbon dating of the skull and mandible of the Razboinichya canid conducted in three independent laboratories resulted in highly compatible ages, with average value of ca. 33,000 cal BP. CONCLUSIONS/SIGNIFICANCE: The Razboinichya Cave specimen appears to be an incipient dog that did not give rise to late Glacial-early Holocene lineages and probably represents wolf domestication disrupted by the climatic and cultural changes associated with the LGM. The two earliest incipient dogs from Western Europe (Goyet, Belguim and Siberia (Razboinichya, separated by thousands of kilometers, show that dog domestication was multiregional, and thus had no single place of

  14. High- and low-Cr chromitite and dunite in a Tibetan ophiolite: evolution from mature subduction system to incipient forearc in the Neo-Tethyan Ocean

    Science.gov (United States)

    Xiong, Qing; Henry, Hadrien; Griffin, William L.; Zheng, Jian-Ping; Satsukawa, Takako; Pearson, Norman J.; O'Reilly, Suzanne Y.

    2017-06-01

    The microstructures, major- and trace-element compositions of minerals and electron backscattered diffraction (EBSD) maps of high- and low-Cr# [spinel Cr# = Cr3+/(Cr3+ + Al3+)] chromitites and dunites from the Zedang ophiolite in the Yarlung Zangbo Suture (South Tibet) have been used to reveal their genesis and the related geodynamic processes in the Neo-Tethyan Ocean. The high-Cr# (0.77-0.80) chromitites (with or without diopside exsolution) have chromite compositions consistent with initial crystallization by interaction between boninitic magmas, harzburgite and reaction-produced magmas in a shallow, mature mantle wedge. Some high-Cr# chromitites show crystal-plastic deformation and grain growth on previous chromite relics that have exsolved needles of diopside. These features are similar to those of the Luobusa high-Cr# chromitites, possibly recycled from the deep upper mantle in a mature subduction system. In contrast, mineralogical, chemical and EBSD features of the Zedang low-Cr# (0.49-0.67) chromitites and dunites and the silicate inclusions in chromite indicate that they formed by rapid interaction between forearc basaltic magmas (MORB-like but with rare subduction input) and the Zedang harzburgites in a dynamically extended, incipient forearc lithosphere. The evidence implies that the high-Cr# chromitites were produced or emplaced in an earlier mature arc (possibly Jurassic), while the low-Cr# associations formed in an incipient forearc during the initiation of a new episode of Neo-Tethyan subduction at 130-120 Ma. This two-episode subduction model can provide a new explanation for the coexistence of high- and low-Cr# chromitites in the same volume of ophiolitic mantle.

  15. July 2012 Greenland melt extent enhanced by low-level liquid clouds.

    Science.gov (United States)

    Bennartz, R; Shupe, M D; Turner, D D; Walden, V P; Steffen, K; Cox, C J; Kulie, M S; Miller, N B; Pettersen, C

    2013-04-04

    Melting of the world's major ice sheets can affect human and environmental conditions by contributing to sea-level rise. In July 2012, an historically rare period of extended surface melting was observed across almost the entire Greenland ice sheet, raising questions about the frequency and spatial extent of such events. Here we show that low-level clouds consisting of liquid water droplets ('liquid clouds'), via their radiative effects, played a key part in this melt event by increasing near-surface temperatures. We used a suite of surface-based observations, remote sensing data, and a surface energy-balance model. At the critical surface melt time, the clouds were optically thick enough and low enough to enhance the downwelling infrared flux at the surface. At the same time they were optically thin enough to allow sufficient solar radiation to penetrate through them and raise surface temperatures above the melting point. Outside this narrow range in cloud optical thickness, the radiative contribution to the surface energy budget would have been diminished, and the spatial extent of this melting event would have been smaller. We further show that these thin, low-level liquid clouds occur frequently, both over Greenland and across the Arctic, being present around 30-50 per cent of the time. Our results may help to explain the difficulties that global climate models have in simulating the Arctic surface energy budget, particularly as models tend to under-predict the formation of optically thin liquid clouds at supercooled temperatures--a process potentially necessary to account fully for temperature feedbacks in a warming Arctic climate.

  16. Contrasting melt equilibration conditions across Anatolia

    Science.gov (United States)

    Reid, Mary; Delph, Jonathan; Schleiffarth, W. Kirk; Cosca, Michael

    2017-04-01

    The widespread mafic volcanism, elevated crustal temperatures, and plateau-type topography in Central Anatolia, Turkey, could collectively be the result of lithospheric delamination, mantle upwelling, and tectonic escape in response to Arabian-Anatolian plate collision. We used the results from basalt geochemistry and a passive-source broadband seismic experiment obtained as part of an international collaborative effort (Continental Dynamics - Central Anatolia Tectonics) to investigate the crust-mantle structure and melting conditions associated with the Quaternary Hasandag Monogenic Cluster (HMC) south and west of Hasandag volcano. The HMC is unusually mafic, not only for Central Anatolia but globally, enabling meaningful comparisons between geochemical and seismic interpretations of mantle conditions. HMC basalts are characterized by orogenic signatures that could have originated (1) in mantle wedge that, after stagnating because of collision, was remobilized south and upward as a result of rollback of the African slab or, alternatively (2) by piecemeal foundering of residual mantle lithosphere into convecting upper mantle, producing small-scale convection and associated decompression melting. Melt equilibration conditions for the HMC are hot (TP ˜1335-1250˚ C, assuming 1-4 wt.% H2O) and shallow (P = 1.1 to 1.6 GPa), approaching those for MORB. Shear wave velocities are relatively constant at ˜4.1 km/s between the Moho and a depth of ˜45-50 km (˜1.4 GPa; Fig. 6), below which Vs increases with increasing depth. We infer that a melt-perfused mantle lid could be locally present between 40 and 55 km. In contrast to Central Anatolia, estimated equilibration conditions for Western Anatolia and Eastern Anatolia (east of the Inner Tauride Suture) mantle melts are hotter (by ≥60˚ C) and deeper (mostly by 0.6-1.0 GPa). They also have chemical signatures that, unlike Central Anatolia, are similar to those of intraplate basalts. These differences are likely related

  17. Magmatic storage conditions, decompression rate, and incipient caldera collapse of the 1902 eruption of Santa Maria Volcano, Guatemala

    Science.gov (United States)

    Andrews, Benjamin J.

    2014-08-01

    Phase equilibria experiments and analysis of natural pumice and phenocryst compositions indicate the 1902 Santa Maria dacite was stored at ~ 140-170 MPa and 840-850 °C prior to eruption. H2O-saturated, cold-seal experiments conducted in vessels with an intrinsic log fO2 of NNO + 1 ± 0.5 show that the natural phase assemblage (melt + plagioclase + amphibole + orthopyroxene + Fe-Ti oxides + apatite) is stable from approximately 115-140 MPa at temperatures below ~ 825 °C, to ~ 840-860 °C at 150 MPa, to > 850 and Ridolfi et al., 2010) applied to experimental samples suggest two populations of amphiboles, phenocrysts grown during the experiments and inherited xenocrysts, but the pressure-temperature conditions returned by the geothermobarometer are routinely > 50 MPa and > 50 °C greater than experimental run conditions; precise estimates of magmatic conditions based solely upon amphibole composition are likely inaccurate. The experimental results and analysis of natural crystals suggest that although the natural amphiboles likely record a broad range of magmatic conditions, only the lower bounds of that range reflect pre-eruptive storage conditions. Comparison of Santa Maria microlite abundances with decompression experiments examining other silicic systems from the literature suggests that the 1902 dacite decompressed at the rate of ~ 0.005 to 0.01 MPa/s during the eruption. Applying the decompression rate with the previously described eruption rate of approximately 2-3 × 108 kg/s (Williams and Self, 1983; Carey and Sparks, 1986) to the conduit model CONFLOW reveals that the eruption conduit was dike-like with an along-strike length > 1 km. Despite depositing ~ 20 km3 of dacite tephra (equivalent to ~ 8.5 km3 magma), the 1902 eruption did not form an obvious caldera. This work suggests that collapse of the dike-like conduit terminated the eruption, preventing full caldera collapse.

  18. Quantifying variant differences in DNA melting curves: Effects of length, melting rate, and curve overlay.

    Science.gov (United States)

    Li, M; Palais, R A; Zhou, L; Wittwer, C T

    2017-12-15

    High resolution DNA melting of PCR products is a simple technique for sequence variant detection and analysis. However, sensitivity and specificity vary and depend on many factors that continue to be defined. We introduce the area between normalized melting curves as a metric to quantify genotype discrimination. The effects of amplicon size (51-547 bp), melting rate (0.01-0.64 °C/s) and analysis method (curve shape by overlay vs absolute temperature differences) were qualitatively and quantitatively analyzed. To limit experimental variance, we studied a single nucleotide variant with identical predicted wild type and homozygous variant stabilities by nearest neighbor thermodynamic theory. Heterozygotes were easier to detect in smaller amplicons, at faster melting rates, and after curve overlay (superimposition), with some p-values overlay, PCR product size, and analysis method is complicated for homozygote genotype discrimination and is difficult to predict. Similar to temperature cycling in PCR, if the temperature control and temperature homogeneity of the solution are adequate, faster rates improve melting analysis, just like faster rates improve PCR. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Crystallization, recrystallization, and melting lines in syndiotactic polypropylene crystallized from quiescent melt and semicrystalline state due to stress-induced localized melting and recrystallization.

    Science.gov (United States)

    Lu, Ying; Wang, Yaotao; Fu, Lianlian; Jiang, Zhiyong; Men, Yongfeng

    2014-11-13

    Crystalline lamellar thickness in syndiotactic polypropylene (sPP) during crystallization from either isothermal molten or stretching induced localized melt states and during subsequent heating was investigated by means of temperature dependent small-angle X-ray scattering techniques. Well-defined crystallization lines where the reciprocal lamellar thickness is linearly dependent on crystallization temperature were observed. Unlike in the case of polybutene-1 where stretching crystallization line was shifted to direction of much smaller lamellar thickness (Macromolecules 2013, 46, 7874), the stretching induced crystallization line for sPP deviates from its corresponding isothermal crystallization line only slightly. Such phenomenon could be attributed to the fact that both crystallization processes from quiescent melt and stress induced localized melt are mediated in a mesomorphic phase in sPP. Subsequent heating of sPP after crystallization revealed the same melting behavior in both systems for the two kinds of crystallites obtained from either quiescent melt or stretching induced localized melt. Both of them underwent melting and recrystallization when the lamellar thickness was smaller than a critical value and melting directly without changing in thickness when the lamellar thickness was larger than the critical value. The melting behavior in sPP systems can be understood by considering the chain relaxation ability within crystalline phase and also can be used as evidence that the crystallization from molten state and stress-induced crystallization passed through the intermediate phase before forming crystallites.

  20. Melting and Its Influence on the Long-term Evolution of the Lower Mantle Heterogeneities (LLSVP and ULVZ)

    Science.gov (United States)

    Fomin, I.; Tackley, P. J.

    2017-12-01

    Recent investigations have shown mantle solidus close to the range of proposed core-mantle boundary (CMB) temperatures (e.g. [Andrault et al., 2011, 2014], [de Koker et al., 2013]). Certain fraction of distinct rocks may reduce the effective melting temperature to values below the CMB temperature. It is especially true for iron enriched materials such as MORB [Nomura et al., 2011], BIF [Kato et al., 2016], iron-rich periclase [Boukare et al., 2015] and other rock species used to explain observed seismic anomalies. Computer simulations allow to study evolution and stability for chemically distinct piles proposed from geophysical data. Previous researches (e.g. [Mulyukova et al., 2015]) found those piles stirring in several hundreds of Ma. Our investigation adds influence of melting and following chemical differentiation on preservation of such structures.We present StagYY code [Tackley et al., 2008] with extended set of routines to model melting, melt redistribution and melt-dependent rheology in addition to solid-state mantle convection to reveal fate of chemically distinct piles in long-term (millions of years) perspective. A new point of our approach is usage of chemically independent oxides to describe rock composition and physical properties. Thin layers homogenize in few tens of millions of years despite whether melting happens or not. Thick structures (like periclase piles proposed for ULVZ [Wicks et al., 2010] or MORB-bearing domes for LLSVP [Ohta et al., 2008]) undergo partial melting if CMB temperature is above 3700K. Melt migration results in extraction of fusible components and therefore segregation of iron-enriched material. However, we weren't able to obtain any stabilized layer of iron-rich partially molten material at the CMB, because ongoing interaction and reequilibration of melt and solid results in buoyant liquids spreading to the adjacent mantle. Rheological influence of melt on bulk rock properties reduces time pile can exist.Our modeling puts

  1. Melting heat transport of nanofluidic problem over a Riga plate with erratic thickness: Use of Keller Box scheme

    Directory of Open Access Journals (Sweden)

    Z. Iqbal

    Full Text Available Present article is a study of stagnation point flow over Riga plate with erratic thickness. Riga plate is an electromagnetic surface in which electrodes are assembled alternatively. This arrangement generates electromagnetic hydrodynamic behavior in the fluid flow. This is an attempt to investigate influence of melting heat, thermal radiation and viscous dissipation effects on Riga plate. A traversal electric and magnetic fields are produced by Riga plate. It causes Lorentz force parallel to wall which contributes in directing flow pattern. Physical problem is modeled and reduced nonlinear system is solved numerically. Comparative analysis is carried out between solutions obtained by Keller Box Method and shooting technique with Runge-Kutta Fehlberg method of order 5. It is noted that melting heat transfer reduces temperature distribution whereas radiation parameter upsurge it. Velocity is accelerated by modified Hartman number and Eckert number contributes in raising temperature. Keywords: Keller Box method, Computational design, Melting heat transfer, Stagnation point, Viscous dissipation, Thermal radiation

  2. Soft-mode behavior and incipient ferroelectricity in Na.sub.1/2./sub.Bi.sub.1/2./sub.Cu.sub.3./sub.Ti.sub.4./sub.O.sub.12./sub..

    Czech Academy of Sciences Publication Activity Database

    Ferrarelli, M.C.; Nuzhnyy, Dmitry; Sinclair, D.C.; Kamba, Stanislav

    2010-01-01

    Roč. 81, č. 22 (2010), 224112/1-224112/7 ISSN 1098-0121 R&D Projects: GA ČR(CZ) GA202/09/0682 Institutional research plan: CEZ:AV0Z10100520 Keywords : infrared and terahertz spectroscopy * soft mode * incipient ferroelectrics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.772, year: 2010

  3. Lessons learnt from FARO/TERMOS corium melt quenching experiments

    Energy Technology Data Exchange (ETDEWEB)

    Magallon, D.; Huhtiniemi, I.; Hohmann, H. [Commission of the European Communities, Ispra (Italy). Joint Research Center

    1998-01-01

    The influence of melt quantity, melt composition, water depth and initial pressure on quenching is assessed on the basis of seven tests performed in various conditions in the TERMOS vessel of the FARO facility at JRC-Ispra. Tests involved UO{sub 2}-based melt quantities in the range 18-176 kg at a temperature of approximately 3000 K poured into saturated water. The results suggest that erosion of the melt jet column is an efficient contributor to the amount of break-up, and thus quenching, for large pours of corium melt. The presence of Zr metal in the melt induced a much more efficient quenching than in a similar test with no Zr metal, attributed to the oxidation of the Zr. Significant amounts of H{sub 2} were produced also in tests with pure oxidic melts (e.g. about 300 g for 157 kg melt). In the tests at 5.0 and 2.0 MPa good mixing with significant melt break-up and quenching was obtained during the penetration in the water. At 0.5 MPa, good penetration of the melt into the water could still be achieved, but a jump in the vessel pressurisation occurred when the melt contacted the bottom and part (5 kg) of the debris was re-ejected from the water. (author)

  4. Rheo-electrical approximate simulation of monocrystal growth from the melt

    International Nuclear Information System (INIS)

    Vernois, G.

    1969-01-01

    On a two-dimensional model, the advantages of rheo-electrical simulation for studying monocrystal growth from the melt are pointed out. In the case of an opaque body, it is always possible to make a fairly exact model. As regards a transparent body, the simulation of radiation thermal exchange is fairly difficult. It is shown how the plans of a constant level complex crucible are established. (author) [fr

  5. Physical properties of steel and concrete up to melting and ablation

    International Nuclear Information System (INIS)

    Schneider, U.; Diederichs, U.

    1981-01-01

    The relevant physical properties of typical steels and concretes which are used in HTGR constructional design are presented. Special consideration has been given to the properties and phenomena concerning thermal behaviour e.g. thermal diffusivity and conductivity, heat capacity, density, thermal expansion and decomposition effects. Data from the literature and recent test results will be discussed. A temperature range from 20 0 C up to the melting points is considered. (orig./HP)

  6. Nanoparticle-induced unusual melting and solidification behaviours of metals

    Science.gov (United States)

    Ma, Chao; Chen, Lianyi; Cao, Chezheng; Li, Xiaochun

    2017-01-01

    Effective control of melting and solidification behaviours of materials is significant for numerous applications. It has been a long-standing challenge to increase the melted zone (MZ) depth while shrinking the heat-affected zone (HAZ) size during local melting and solidification of materials. In this paper, nanoparticle-induced unusual melting and solidification behaviours of metals are reported that effectively solve this long-time dilemma. By introduction of Al2O3 nanoparticles, the MZ depth of Ni is increased by 68%, while the corresponding HAZ size is decreased by 67% in laser melting at a pulse energy of 0.18 mJ. The addition of SiC nanoparticles shows similar results. The discovery of the unusual melting and solidification of materials that contain nanoparticles will not only have impacts on existing melting and solidification manufacturing processes, such as laser welding and additive manufacturing, but also on other applications such as pharmaceutical processing and energy storage.

  7. Electrically isolated, high melting point, metal wire arrays and method of making same

    Science.gov (United States)

    Simpson, John T.; Cunningham, Joseph P.; D'Urso, Brian R.; Hendricks, Troy R.; Schaeffer, Daniel A.

    2016-01-26

    A method of making a wire array includes the step of providing a tube of a sealing material and having an interior surface, and positioning a wire in the tube, the wire having an exterior surface. The tube is heated to soften the tube, and the softened tube is drawn and collapsed by a mild vacuum to bring the interior surface of the tube into contact with the wire to create a coated wire. The coated wires are bundled. The bundled coated wires are heated under vacuum to fuse the tube material coating the wires and create a fused rod with a wire array embedded therein. The fused rod is cut to form a wire array. A wire array is also disclosed.

  8. Structure changes in UO2(hfa)2 NH3 near the melting point

    International Nuclear Information System (INIS)

    Johnson, D.A.; Taylor, J.C.; Waugh, A.B.

    1982-01-01

    A reversible colour change from lemon-yellow to orange was observed for polycrystalline UO 2 (hfa) 2 NH 3 at 100 0 C (hfa = (1,1,1,5,5,5-hexafluoro-2,4-pentanedione)). The changes in the X-ray powder pattern between -196 0 and 130 0 C were followed with a Guinier-Simon focussing camera. The colour change was not due to an α - β type structural transition as found earlier in α and β-UO 2 (hfa) 2 tmp (tmp = trimethyl phosphate), but was considered to be due to changes in the hydrogen bonding of the ammonia molecules. (author)

  9. Temperature calibration procedure for thin film substrates for thermo-ellipsometric analysis using melting point standards

    NARCIS (Netherlands)

    Kappert, Emiel; Raaijmakers, Michiel; Ogieglo, Wojciech; Nijmeijer, Arian; Huiskes, Cindy; Huiskes, C.; Benes, Nieck Edwin

    2015-01-01

    Precise and accurate temperature control is pertinent to studying thermally activated processes in thin films. Here, we present a calibration method for the substrate–film interface temperature using spectroscopic ellipsometry. The method is adapted from temperature calibration methods that are well

  10. Simulation of melt spreading in consideration of phase transitions

    International Nuclear Information System (INIS)

    Spengler, C.

    2002-01-01

    The analysis of melt spreading and relocation phenomena in the containment of LWR power plants in case of hypothetical severe accidents leading to core melting is an important issue for reactor safety investigations. For the simulation of melt spreading the code LAVA has been developed on the basis of a method from the related subject of volcanology by adding more detailed models for heat transfer phenomena and flow rheology. The development is supported by basic analysis of the spreading of gravity currents as well as experimental investigations of the rheology of solidifying melts. These exhibit strong non-Newtonian effects in case of a high content of solids in the freezing melt. The basic model assumption in LAVA is the ideal Bingham plastic approach to the non-Newtonian, shear-thinning characteristic of solidifying melts. For the recalculation of melt spreading experiments, the temperature-dependent material properties for solidifying melt mixtures have been calculated using correlations from the literature. With the parameters and correlations for the rheological material properties approached by results from literature, it was possible to recalculate successfully recent spreading experiments with simulant materials and prototypic reactor core materials. An application to the behaviour of core melt in the reactor cavity assumed a borderline case for the issue of spreading. This limit is represented by melt conditions (large solid fraction, low volume flux), under which the melt is hardly spreadable. Due to the persistent volume flux the reactor cavity is completely, but inhomogeneously filled with melt. The degree of inhomogeneity is rather small, so it is concluded, that for the long-term coolability of a melt pool in narrow cavities the spreading of melt will probably have only negligible influence. (orig.)

  11. Revisiting the Potential of Melt Pond Fraction as a Predictor for the Seasonal Arctic Sea Ice Extent Minimum

    Science.gov (United States)

    Liu, Jiping; Song, Mirong; Horton, Radley M.; Hu, Yongyun

    2015-01-01

    The rapid change in Arctic sea ice in recent decades has led to a rising demand for seasonal sea ice prediction. A recent modeling study that employed a prognostic melt pond model in a stand-alone sea ice model found that September Arctic sea ice extent can be accurately predicted from the melt pond fraction in May. Here we show that satellite observations show no evidence of predictive skill in May. However, we find that a significantly strong relationship (high predictability) first emerges as the melt pond fraction is integrated from early May to late June, with a persistent strong relationship only occurring after late July. Our results highlight that late spring to mid summer melt pond information is required to improve the prediction skill of the seasonal sea ice minimum. Furthermore, satellite observations indicate a much higher percentage of melt pond formation in May than does the aforementioned model simulation, which points to the need to reconcile model simulations and observations, in order to better understand key mechanisms of melt pond formation and evolution and their influence on sea ice state.

  12. Lattice stability and high-pressure melting mechanism of dense hydrogen up to 1.5 TPa

    KAUST Repository

    Geng, Hua Y.

    2015-09-01

    © 2015 American Physical Society. Lattice stability and metastability, as well as melting, are important features of the physics and chemistry of dense hydrogen. Using ab initio molecular dynamics (AIMD), the classical superheating limit and melting line of metallic hydrogen are investigated up to 1.5 TPa. The computations show that the classical superheating degree is about 100 K, and the classical melting curve becomes flat at a level of 350 K when beyond 500 GPa. This information allows us to estimate the well depth and the potential barriers that must be overcome when the crystal melts. Inclusion of nuclear quantum effects (NQE) using path integral molecular dynamics (PIMD) predicts that both superheating limit and melting temperature are lowered to below room temperature, but the latter never reaches absolute zero. Detailed analysis indicates that the melting is thermally activated, rather than driven by pure zero-point motion (ZPM). This argument was further supported by extensive PIMD simulations, demonstrating the stability of Fddd structure against liquefaction at low temperatures.

  13. Extended T-index models for glacier surface melting: a case study from Chorabari Glacier, Central Himalaya, India

    Science.gov (United States)

    Karakoti, Indira; Kesarwani, Kapil; Mehta, Manish; Dobhal, D. P.

    2016-10-01

    Two enhanced temperature-index (T-index) models are proposed by incorporating meteorological parameters viz. relative humidity, wind speed and net radiation. The models are an attempt to explore different climatic variables other than temperature affecting glacier surface melting. Weather data were recorded at Chorabari Glacier using an automatic weather station during the summers of 2010 (July 10 to September 10) and 2012 (June 10 to October 25). The modelled surface melt is validated against the measured point surface melting at the snout. Performance of the developed models is evaluated by comparing with basic temperature-index model and is quantified through different efficiency criteria. The results suggest that proposed models yield considerable improvement in surface melt simulation . Consequently, the study reveals that glacier surface melt depends not only on temperature but also on weather parameters viz. relative humidity, wind speed and net radiation play a significant role in glacier surface melting. This approach provides a major improvement on basic temperature-index method and offers an alternative to energy balance model.

  14. Myofascial trigger point pain.

    Science.gov (United States)

    Jaeger, Bernadette

    2013-01-01

    Myofascial trigger point pain is an extremely prevalent cause of persistent pain disorders in all parts of the body, not just the head, neck, and face. Features include deep aching pain in any structure, referred from focally tender points in taut bands of skeletal muscle (the trigger points). Diagnosis depends on accurate palpation with 2-4 kg/cm2 of pressure for 10 to 20 seconds over the suspected trigger point to allow the referred pain pattern to develop. In the head and neck region, cervical muscle trigger points (key trigger points) often incite and perpetuate trigger points (satellite trigger points) and referred pain from masticatory muscles. Management requires identification and control of as many perpetuating factors as possible (posture, body mechanics, psychological stress or depression, poor sleep or nutrition). Trigger point therapies such as spray and stretch or trigger point injections are best used as adjunctive therapy.

  15. Recent results in characterization of melt-grown and quench-melt- grown YBCO superconductors

    International Nuclear Information System (INIS)

    Balachandran, U.; Poeppel, R.B.; Gangopadhyay, A.K.

    1992-02-01

    From the standpoint of applications, melt-grown (MG) and quench-melt-grown (QMG) bulk YBCO superconductors are of considerable interest. In this paper, we studied the intragranular critical current density (J c ), the apparent pinning potential (U o ), and the irreversibility temperature (T irr ) of MG and QMG samples and compared the results to those for conventionally sintered YBCO. A systematic increase in U o and a slower drop in J c with temperature indicate a systematic improvement in flux-pinning properties in progressing from the sintered YBCO to QMG and MG samples. Weaker pinning is observed in the QMG YBCO than in the MG samples

  16. Quality improvement of melt extruded laminar systems using mixture design.

    Science.gov (United States)

    Hasa, D; Perissutti, B; Campisi, B; Grassi, M; Grabnar, I; Golob, S; Mian, M; Voinovich, D

    2015-07-30

    This study investigates the application of melt extrusion for the development of an oral retard formulation with a precise drug release over time. Since adjusting the formulation appears to be of the utmost importance in achieving the desired drug release patterns, different formulations of laminar extrudates were prepared according to the principles of Experimental Design, using a design for mixtures to assess the influence of formulation composition on the in vitro drug release from the extrudates after 1h and after 8h. The effect of each component on the two response variables was also studied. Ternary mixtures of theophylline (model drug), monohydrate lactose and microcrystalline wax (as thermoplastic binder) were extruded in a lab scale vertical ram extruder in absence of solvents at a temperature below the melting point of the binder (so that the crystalline state of the drug could be maintained), through a rectangular die to obtain suitable laminar systems. Thanks to the desirability approach and a reliability study for ensuring the quality of the formulation, a very restricted optimal zone was defined within the experimental domain. Among the mixture components, the variation of microcrystalline wax content played the most significant role in overall influence on the in vitro drug release. The formulation theophylline:lactose:wax, 57:14:29 (by weight), selected based on the desirability zone, was subsequently used for in vivo studies. The plasma profile, obtained after oral administration of the laminar extruded system in hard gelatine capsules, revealed the typical trend of an oral retard formulation. The application of the mixture experimental design associated to a desirability function permitted to optimize the extruded system and to determine the composition space that ensures final product quality. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Ice shelf melt rates in Greenland and Antarctica using time-tagged digital imagery from World View and TanDEM-X

    Science.gov (United States)

    Charolais, A.; Rignot, E. J.; Milillo, P.; Scheuchl, B.; Mouginot, J.

    2017-12-01

    The floating extensions of glaciers, or ice shelves, melt vigorously in contact with ocean waters. Melt is non uniform, with the highest melt taking place in the deepest part of the cavity, where thermal forcing is the greatest because of 1) the pressure dependence of the freezing point of the seawater/ice mixture and 2) subglacial water injects fresh, buoyant, cold melt water to fuel stronger ice-ocean interactions. Melt also forms along preferential channels, which are not stationary, and create lines of weakness in the shelf. Ice shelf melt rates have been successfully measured from space over the entire Antarctic continent and on the ice shelves in Greenland using an Eulerian approach that combines ice thickness, ice velocity vectors, surface mass balance data, and measurements of ice thinning rates. The Eulerian approach is limited by the precision of the thickness gradients, typically of a few km, and requires significant spatial averaging to remove advection effects. A Lagrangian approach has been shown to be robust to advection effects and provides higher resolution details. We implemented a Lagrangian methodology for time-tagged World View DEMs by the Polar Geoscience Center (PGS) at the University of Minnesota and time-tagged TanDEM-X DEMs separated by one year. We derive melt rates on a 300-m grid with a precision of a few m/yr. Melt is strongest along grounding lines and along preferred channels. Channels are non-stationary because melt is not the same on opposite sides of the channels. Examining time series of data and comparing with the time-dependent grounding line positions inferred from satellite radar interferometry, we evaluate the magnitude of melt near the grounding line and even within the grounding zone. A non-zero melt rate in the grounding zone has vast implications for ice sheet modeling. This work is funded by a grant from NASA Cryosphere Program.

  18. Properties of aspirin modified enteric polymer prepared by hot-melt mixing.

    Science.gov (United States)

    Chomcharn, Nonjaros; Xanthos, Marino

    2013-06-25

    Melt mixing in batch equipment or continuous extruders is a technique that recently gained the attention of the pharmaceutical industry. The present work has employed hot-melt mixing to prepare a modified enteric matrix, as a delayed-release dosage form. Different concentrations of aspirin (ASP) ranging from 10 to -30% (w/w) were melt-mixed with a plasticized methacrylic acid copolymer, Eudragit(®) L100-55 in a batch mixer for 5 min at 100 °C which is above the plasticized polymer's glass transition temperature and below the ASP's melting point. The samples were cooled down to room temperature and compressed to thin discs. Processing ASP with Eudragit(®) L100-55 did not promote hydrolysis of ASP. X-ray diffraction spectra obtained at room temperature revealed that aspirin was present in a crystalline state. However, at elevated temperatures the dissolved aspirin displayed a plasticizing effect by reducing the glass transition temperature (Tg) and lowering the viscosity of the polymer in proportion to its increasing concentration. The addition of ASP altered to some extent the rheological behavior of the polymer from rubbery to viscous. However, the amount of ASP loading had no significant impact on the dissolution profiles. The samples met USP delayed-release requirements and the API release mechanism was shown to be diffusion dominant. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Abnormal Winter Melting of the Arctic Sea Ice Cap Observed by the Spaceborne Passive Microwave Sensors

    Science.gov (United States)

    Lee, Seongsuk; Yi, Yu

    2016-12-01

    The spatial size and variation of Arctic sea ice play an important role in Earth’s climate system. These are affected by conditions in the polar atmosphere and Arctic sea temperatures. The Arctic sea ice concentration is calculated from brightness temperature data derived from the Defense Meteorological Satellite program (DMSP) F13 Special Sensor Microwave/Imagers (SSMI) and the DMSP F17 Special Sensor Microwave Imager/Sounder (SSMIS) sensors. Many previous studies point to significant reductions in sea ice and their causes. We investigated the variability of Arctic sea ice using the daily sea ice concentration data from passive microwave observations to identify the sea ice melting regions near the Arctic polar ice cap. We discovered the abnormal melting of the Arctic sea ice near the North Pole during the summer and the winter. This phenomenon is hard to explain only surface air temperature or solar heating as suggested by recent studies. We propose a hypothesis explaining this phenomenon. The heat from the deep sea in Arctic Ocean ridges and/ or the hydrothermal vents might be contributing to the melting of Arctic sea ice. This hypothesis could be verified by the observation of warm water column structure below the melting or thinning arctic sea ice through the project such as Coriolis dataset for reanalysis (CORA).

  20. Abnormal Winter Melting of the Arctic Sea Ice Cap Observed by the Spaceborne Passive Microwave Sensors

    Directory of Open Access Journals (Sweden)

    Seongsuk Lee

    2016-12-01

    Full Text Available The spatial size and variation of Arctic sea ice play an important role in Earth’s climate system. These are affected by conditions in the polar atmosphere and Arctic sea temperatures. The Arctic sea ice concentration is calculated from brightness temperature data derived from the Defense Meteorological Satellite program (DMSP F13 Special Sensor Microwave/Imagers (SSMI and the DMSP F17 Special Sensor Microwave Imager/Sounder (SSMIS sensors. Many previous studies point to significant reductions in sea ice and their causes. We investigated the variability of Arctic sea ice using the daily and monthly sea ice concentration data from passive microwave observations to identify the sea ice melting regions near the Arctic polar ice cap. We discovered the abnormal melting of the Arctic sea ice near the North Pole even during the summer and the winter. This phenomenon is hard to explain only surface air temperature or solar heating as suggested by recent studies. We propose a hypothesis explaining this phenomenon. The heat from the deep sea in Arctic Ocean ridges and/or the hydrothermal vents might be contributing to the melting of Arctic sea ice. This hypothesis could be verified by the observation of warm water column structure below the melting or thinning arctic sea ice through the project such as Coriolis dataset for reanalysis (CORA.